Because the central guy can't control those corporate entities directly. He primarily wields political power, not financial power. There's a tension between the two.

Musk (financial power) is currently winning out over Steve Bannon (political power). Musk doing that Nazi salute brought a lot of MAGA people underneath him who were otherwise getting worried that Musk was the wrong kind of authoritarian.

Financial power might win in the end, and the reason is that Trump is a doddering old man. This is unique; it's not quite following the same script as Nazi Germany, where Hitler was relatively young and still had the same mental faculties he always did (even if those faculties were twisted).