The issues has been discussed in multiple threads. I think I went into the details in this post though.
TLDR; version is there was no specific laws for geothermal power, and as a result, the law governing hotspring tourism was used to regulate geothermal power drilling in the past, and that made it impossible to do anything productive. Of course, any party in control of the legislative yuan could have changed that in the past 50 years. The KMT never did anything about it though. It was the Tsai government that got things done, and that’s why we are seeing more geothermal development in recent years.