Both Michigan and Indiana have state inspection programs for all charter vessels regardless of number of passengers.
Since many US scuba charters operate in and out of Michigan waters depending on the dive site I think most end up getting inspected.
[.....]
I don't recall if Canadian rules in the Great Lakes require any kind of inspections.
Of course we do inspections in Canada.
Passenger Vessels FAQ - Transport Canada
Are small non-pleasure vessels inspected for safety by the government?
Small non-pleasure vessels may be inspected by Transport Canada at any time. Larger vessels - such as those carrying more than 12 passengers - are inspected annually.