Well... depends. Federal elections have extreme restrictions around the amount of money that can can be contributed to a campaign. Any money changing hands outside of a campaign contribution falls into the category of bribery. Claims of "major corporate funding" and the like are almost always pure conjecture. The risks are too great. ..... rolls uphill in federal indictments. Individuals and unprosecutable foreign investors are far more likely to assume such a responsibility, and they have no real reason to believe they'll be caught.
This is one of the areas where the Fed actually has it better than their local counterparts. Local governments, particularly un-elected bodies such as a city Public Health Commision, tend to have rich friends.
Whatever you are vaping I want some. Ever since SCOTUS granted the corps personhood most of what you are saying went out the window. Super PAC's don't have to disclose their private donors and since corps are now citizens they are included in the anonymous. Even before that who do you think was backing these foreign contributors? I'll give you a hint...the same ones that are sending the jobs overseas.