Wind, Mobilicity etc are all new (they popped in existence after our AWS auction), and only have limited coverage (outside of their coverage area, they all have sharage agreements with one of the big three). For example, Wind only services a few of the major cities, but the moment you leave Wind's towers range, you're switched over the Roger's network and are charged hilarious fees.
And our Big Three (Bell, Rogers, and Telus) are even worse than youres. It's beyond ridiculous.
Also of note that with Bell and Telus's new 3G network, Bell built out the Eastern half (its home base) and Telus built the Western, and they each share their networks with the other. That way, they could build out a next-generation network for half the cost, and twice as fast.
There are also a large number of non-major players (such as SaskTel in Saskatchewan, Aliant in the Maritimes, and so on) that are largely irrelevant unless you live in their coverage areas.
