This happened long before "streaming audio" or 'apps' were a real thing. Also I live in Canada and drove in USA & Canada. The roaming charges were astronomical and didn't include data. The situation isn't much better now, but atleast I have USA data coverage upto 1GB.

Cellphone plan options in Canada are punitive and oppressive. Getting coverage in USA & Canada is painful.

When I was driving in the States, data-usage was measured in kB.