A corporation is just one or more people pooling their resources for legal and accounting purposes. Theres nothing inherently virtuous or evil about the concept.

Going back to my original example, why is it okay for a media company to use their platform and resources to promote whatever speech they want promoted, but I can’t use money I made selling hot dogs to do the same?

The only way to make the playing field fair is to allow everybody to take part. Otherwise you have a handful of media companies with outsized control of indirect messaging.

>A corporation is just one or more people pooling their resources for legal and accounting purposes.

It is not. That's one aspect, but another major aspect is that those individuals pooling their resources are not liable for the corporation's actions. This immunity from liability for their collective responsibility has a price, and part of that price is that the corporation should not be used in an attempt to manipulate elected officials. Corporations are not people for the same reason that you are not a blood cell. The whole is not only greater than the sum of the parts, it is materially different.

>The only way to make the playing field fair is to allow everybody to take part.

This is one solution, I'm not sure it is truly the only solution.

Why do we treat media companies differently? Maybe we shouldn't. Newspapers traditionally had political coverage, and had no restrictions on political commentary. As a result, their owners wielded enormous political power. Then radio and TV arrived on the scene, and had to abide by the "equal time" rule due to their government-granted broadcast licenses. The internet upended all that. We should look for a good answer, not just an expedient one.