[Vigilanteman]

First I heard of that. Propane tank exchanges are ubiquitous around here because outdoor barbecuing is so popular. I know of at least eight places within a five mile radius, four of those at gas stations. You can either buy an entirely new propane tank, or pay a lot less to get a full one by turning in your empty.

How did the Canadians collect road taxes on such propane sales?

[Squawk 8888]

The propane pumps for automotive refuelling are different from the portable tank fillers. AFAIK the taxes are the same for either use, but if not I’m sure there’s an audit trail built into the pumps.