Why cant geothermal or hydroelectric plants be built just anywhere?

Geothermal plants must be built where hot rocks are found at reasonably shallow depths so it is possible to drill down to them and pump water through them to make steam.

Hydroelectric plants must be built where the land form will contain the reservoir which will form behind the dam, where the contained reservoir will be large enough to manage power production in spite of the natural variations in the volume of water flowing in the dammed river, and, of course, they must be built where there is a river. It also has to be possible to build the dam high enough to produce adequate pressure for operation of the turbines which will turn the generators that will produce the electricity.