I don't know if sloppy practice explains the earthquakes in Oklahoma, though.
The groundwater contamination is a serious issue, that needs to be resolved, probably through more frequent inspections and higher fines. The earthquakes are a trivial problem. They are small, and transitory. Once the frackers move on, the earthquakes will stop. Fracking has generated over a million jobs, adds hundreds of billions of domestic production to the US economy every year, and, by replacing coal with gas, has done more to reduce CO2 emissions than all other efforts combined. If the price of that is a few rattled windows in rural Oklahoma, then so be it.