~45% of people work for companies of less than 500 people, ~12% for the govrnment (federal, state, local), ~6% are self employed. That leaves less than a half for all the companies >500, and only a tiny minority of them have an outsized influence on politics.
EDIT: Also, if there were no big corporations, people would still work and pay taxes. No sane statesman would purposefully build their countries economy on non-state-controlled megacorps.
I don't know of any other way the government makes money other than riding on the back of corporations.
So yes, from the governments POV, using eminent domain to make corporations richer also has the direct effect of making the government richer.
Just think about it a little bit.