I don't know about elsewhere, but in Australia CSG wells are often operated under a coal mining permit (vs oil/gas drilling permit) where the drilling operations, casing requirements, testing/audit trails etc. designed to protect aquifers (and well integrity) are nowhere near as strict as conventional oil & gas.
Hell, the crews drilling CSG don't even have basic understanding of well control theory (or enough instrumentation on the rig to detect problems) - hence the occasional uncontrolled blowouts, mitigated only by the fact that these CSG wells are slimhole vs conventional.
I'd much rather live next to a fracked conventional oil & gas well which has been cased & cemented according to the design of certified petroleum engineers, pressure-tested with all the results lodged properly with government authorities to depths far exceeding any of the local aquifers - than a dodgy CSG well cemented by amateurs who work to rough guidelines "appropriate for the area", who write more documentation on their invoicing than on any actual data collection...
Source: I worked with an oil & gas service company 2006-2008...