"But your (OP) comment that you shouldn't be expected to use a DVM is a cop-out IMO."
Sorry, but you are totally incorrect. A user should be able to rely on any electrical installation meeting the published standards and plug in without having to check those standards have been met. A DVM is a test meter designed to be used by qualified personnel and is not a consumer item in this situation.
Do you get your city water supply checked each time you drink water, or do you get all your fruit and vegetables measured for contamination, or check that the fuel pump is dispensing gas rather than water. No, of course you don't. A RV park owner has a contractural obligation and duty of care to ensure that all parts of the premises meet current regulations.
