[abrezas]

One of the problems with the Canadian tax law, was that Canada has to remain competitive to the same-language speaking country south of its borders that has a bigger and more advanced stock exchange. It is explained in the last section of your second link.

The same problems will not be necessarily manifested if the law is applied in the US, especially if Canada has similar laws. However, the points of the first link seem to hold.

[yummyfajitas]

That only applies to cross listed symbols (e.g. Blackberry), currencies, etc.

The fact that one can shift trading in cross listed symbols to other venues doesn't mean that supply&demand also doesn't reduce market making (thereby increasing costs). In fact, Bernie Sanders explicitly hopes the tax will do exactly that.