[hota_mazi]

> Hiring someone across a national border adds a lot of complexity and cost to the employment process

It's not really true for the US and Canada thanks to Nafta.

[bzbarsky]

You have different tax withholding procedures, differences in labor law and what sort of employment contracts are allowed, differences in mandated benefits (e.g. parental leave).

This is an issue even if you want to hire in more than one US state.

The question is whether all that adds up to "a lot", which is a value judgment.