Are you sure about that? In my experience pretty much everyone can speak standard Mandarin (with the exception of some old people who cant or wont, and some young children who have not gone to school yet.)
I’ve heard people say 中文 國語 普通話 華語 中國話 and a couple of others, but never heard anyone ever say 管語 ever
Just to make sure that I fully come accross as an argumentative sod: ‘Amoy’ is a romanization of 廈門 based on the Hokkien pronunciation of the name of the city which is located in Fujian.
I’d say it’s only true if you haven’t mastered the basics of the writing system. Once you do that, you realize it’s all around you as well. But there’s undoubtedly a learning curve to get there, which is much higher than for phonetic spelling.
After learning Wade Giles pinyin I came to the same conclusion. The first western Mandarin experts weren’t very familiar with spoken Mandarin as it simply wasn’t used much at the time and local pronunciation was probably very diverse. Those early scholars were based in southern China usually.
So called language experts on here tried to poo poo my claims.
But its pretty obvious that Wade-Giles were massively influenced by Hokkien and Cantonese. Either because Mandarin itself was not standardised at the time, or because they had little clue about spoken Mandarin and mixed everything up. There were no recordings they could listen to. They had to learn Chinese from the people around them ~
K instead J (Keelung )
P instead of B (Peking
T instead of D (Tanmshui)
Some of these modern Chinese ‘scholars’ have their heads up their own asses. 
Wade-Giles is based on Beijing dialect
J is ch in WG. The usage of p and t isn’t unusual by linguistic standards, as you can also have additional voiced consonants which would be represented with b and d, like you see in Taiwanese or Thai for example. p’ and t’ serve as the aspirated unvoiced versions of those consonants in WG.
In Hokkien, the words for “beijing” and “danshui” don’t have any more of an English “p” or “t” sound than in Beijing Mandarin. Not sure about Cantonese
Did you look into where Wade and especially Giles spent all their working lives?
So you think the K for J in Keelung was a complete coincidence? I don’t think so. He was heavily influenced by local pronunciation of the place names.
I suggest you DO check how Beijing is pronounced in Cantonese.
You just bought into the made up story after the fact 
.
Presumably those are all postal romanizations?
Damn Wade-Giles. Damn them. Too many ch’s.
Zh=ch
Ch=ch
J=ch
Q=ch
That’s why in the states, they think all Chinese named are Ching-Chong Ching-Chong.
May you burn in hell before you reach paradise.
You seem unwilling to reconsider your clearly erroneous position, so I’ll just leave it there as I’ve cleared it up sufficiently.
Dont get technical and academic on me.
Instead follow my line of reasoning.
No you just said it was Beijing Mandarin but it’s not. Anybody who learned Mandarin to a certain degree could tell that. Later on scholars made up preoposterous stories that K was somehow supposed be pronounced J . That’s just dumb.
If you look into it they were actually using Cantonese and Hokkien (or very heavy influenced localised Mandarin ) to build out their Pinyin system.
A letter in the Independent newspaper last week (Wednesday 21 November), from Shirin Tata of London, explained the spelling and pronunciation of Peking as ‘a close approximation to the Cantonese name for the city (“puck-ing” with a hard “p”)’. This came about, the writer says, because early contacts between Europe and China were with traders and seamen from the south of China, and the Europeans copied their pronunciation for place names. This explanation is similar to that for the origin of the English name for Livorno in Italy: Leghorn (now obsolete), which is a close approximation to the local dialectal form for the name: Ligorno .
A little harsh for the pioneers but yeah their pinyin system was mostly trash. 
Wade-Giles is based on Beijing Mandarin. That’s just a fact and an obvious one if you look at it. You’ve confused WG with the issue of some place names having established romanizations (probably based on southern dialects, sure) that aren’t consistent with Wade-Giles or modern pinyin.
Your line of reasoning - correct me if I am wrong - is that that consonants are messed up in some romanization systems - based on current pronunciations - therefore the Romanizations were not based on Standard Chinese?
Im not cofusing anything I’ve actually researched both of their lives (have you done the same ?) and have provided a very clear explanation as to why their idiosyncratic pinyin system looks the way it does.
They were based on what they thought was Mandarin Chinese or the best local approximation to it . They would have learned from local teachers and their interactions in daily life.
It’s very simple, in Hokkien the J sound is more like K. So their pinyin system used K. It’s not because they were some errant geniuses trying to make our lives harder by using K for a J sound !
But you’re wrong as I’ve explained. Tell me this, why is the English “p” sound p’ in WG? And “t” t’ ?? You haven’t even addressed the obvious error that pinyin “j” is ch in WG and not k.
I’m not wrong…Check how Beijing is pronounced in Cantonese and come back to me.
Why should I? That has nothing to do with WG. No worries! You’ll figure it out sooner or later.
You said it was based on standard Beijing Mandarin.
I gave a good explanation why I believe that isn’t the case with examples. You seem to think that Wade and Giles residing Cantonese and Hokkien speaking areas for much of their lives did not have an influence on their pinyin system, even though there are many examples where it obviously had an influence .
Ok
The problem is, the apostrophes aren’t transcribed in names. That’s why everything sounds like Ching-Chong Ching-Chong to Americans.