IMHO, all equipment installed for a solar job is supplied by the EC/Installer. Including a 'disconnect' to prevent backfeed to the utility, when required.
Rolling back the clock, an exterior disco was installed to prevent backfeed into the grid when it was necessary to terminate the backfeed. As eloquently explained above by Larry C, the newer equipment has technology that automatically prevents 'backfeed' IF and when the utility power is down.
As to what you refer to "backwoods" installs, that may be another issue that I have no experience with, as all work here is permitted & inspected by the municipality, and the utility, with spot checks by the state.