Geothermal heat is usually obtained by drilling very deep bore holes, the heated water, is under pressure under ground so when the bore hole is drilled, the water rushes up the bore as it now has room to expand so the bore hole will have pressure valves at the top to control the flow.
I do not understand why this is not possible underground in coal mines. It is possibly because the water concerned is not under pressure and it is its heat they wish to use, in which case the water may not be under pressure and will not flow out of the rocks without fracking them to provide fissures and crevices for the water to travel along.
But fracking is fracking whether you are doing it for water or gas. If indeed there are any real threats in fracking then fracking for geothermal energy may be potentially more dangerous than fracking for gas as fracking for gas will usually take place at far greater depths than thermal fracking.
Nothing wrong with geothermal power, it is not renewable but it produces no emissions, but in the UK there are only limited areas where it is available and can be used.