The tablet market was very different before the iPad was released so I don't think it's a very fair comparison. Are there figures from the iPad 2 launch?
You can use an AT&T iPad sim and get a $25/month data-only plan. This is what I do with my 3GS when I visit the US, otherwise the costs are extortionate.
Don't tell anyone though. I'd like it to still work the next time I'm in the US...
Excuse me?