For what it's worth, I've lived in the US since the 70s and I don't think I've ever encountered a gas dryer. Could be regional, though.

Utility natural gas does tend to be regional. Where it's available, it's most often much less expensive to use natural gas for heating than electric resistance heating, although you usually have to pay more for the appliances. If electricity is inexpensive, gas is less desirable. Most gas appliances can be adapted to use propane, and propane deliveries are available in a wider area, but you probably want several propane appliances to justify the plumbing and the storage tank.

Electric heat pumps can be more cost effective than gas though, but there's details.

Utility natural gas is obviously pretty widespread across Canada. I've never seen nor heard of a single person with a gas dryer.

Based on my (obviously limited) set of data, I'd certainly argue against "most" dryers being gas-powered.