In the US, Telsa no longer receives any federal tax credit as of January 2020. A few states (including California) still have incentives. In any case, losing the tax credit doesn't seem to have slowed them down.

You only get 250k of tax credits, and both Tesla and GM have already used them. Ford still has some.

To make money with EV you need to produce way more then 250k of cars, so you can absolutely not relay tax credits to improve margins.

Also, Tesla is now competing successfully without tax credits against many companies who still have theirs. Tesla is actually making a pretty good 20% automotive margin, and that is with Model Y still being a small part of sales (and we know that Model Y has better margin).