That's not true, many ISP's in the US have caps, they are just A LOT more reasonable then in Canada. For example I have friends that have caps on Comcast. I believe they are at least 250GB+ a month though.
Here the ISP's design their packages to maximize the amount of people that will go over and scare them into purchasing "assurance" policies (aka extra bandwidth). And the best part is, many people fall for it.
How much does bandwidth cost for ISPs these days? Pennies on the dollar? Whatever, it isn't much and these caps have turned into cash cows for them. No way they ever do away with them. I'm sure if they thought of it back then, they would have put caps on dial-up services.
Full 1 Gbps likely not possible with home gear yet
1Gbps bandwidth would only be good if your home devices could actually use it. Don't mistake a Gigabit ethernet device for one capable of through-putting 1Gbps (the ethernet 1000TX/SX spec limits it to between 60-80% of that at the best of times).
So, until the new crop of 10Gbps ethernet devices hit the market and you upgrade all your NICs, routers, etc. you need to calculate whether 600-800Mbps is even possible with your home gear, let alone whether it is worth the money for such a plan. A true networking geek would bond two Gigabit ethernet devices to use up such a connection's full speed potential.
Is it worth it today? Maybe so, most likely not. In the future? Sign me up!!!