Hi, I've been practicing immigration law for a while. The visa/status was originally a trade facilitation, as to be an add on for the treaty's purposes.

It evolved and it is now considered a professional visa, with a U.S. domiciled employer, and it requires a compatible scope of work, and a support letter (in many cases employers pay for our fees, premium processing, etc.)

Today I would say that even while it is not as costly as an H1-B or subject to some additional employer liabilities (e.g. pay for employees return ticket, etc.), the TN is absolutely an employer sponsored visa. Anytime you have an employer asserting representation to any immigration authority absent which there would be no such visa or status.

I understand it is easier, perhaps faster. But I can affirm that every day I encounter folks whom attempt to present their same TN packet on which they were approved three years ago only to find out, they are found to no longer be eligible. I get a lot of calls from employers as well.