I'm not sure you can attribute that to banking practices, nor am I sure what you mean by 'balance of trade', exactly. But rather than framing this as a geopolitical issue, why not just look for a different way to move money around?
My bank will accept Canadian checks for a reasonable fee, and I haven't had much trouble getting clients to wire in money for larger sums. Lots of Canadian banks allow customers to write checks in USD, which makes things easy, and I'm sure there are lots of other options.
If you are only depositing a $20 check, I wouldn't really expect the banks to very accommodating. Check clearing is expensive and with that amount, you really aren't doing much to encourage international trade, as you mentioned. Further, since you mentioned that you were willing to pay a huge fee just to 'have something to complain about' it seems like you're more interested in griping than actually doing business.