Well, they are saying, EU market is harder to operate in (because everyone pays VAT) than the US market (no VAT, also lower regulatory barriers it seems), and also EU firms have a "home advantage" benefit, for example the regulation is written for their benefit.

So US is easy to sell in for everyone, EU is "hard" to sell in for everyone, but maybe less so for EU car makers. So there is something to this argument, it's not entirely without merit.

Additionally, US car tariff used to be 2.5%, whereas EUs is 10%. The imbalance is short in justification, though across the board, EU and US charge each other similar tariff amounts altogether, so there are other areas where the US charges more.

Whether that justifies broad brush enormous tariffs in everything, and whether US does the same in other industries (defence for example) is an exercise I leave for the trader.