Do unions work against corporate mergers? I’d imagine they do as they tend to work against corporate interests in general but I’m not that well versed in this sort of history.

Unions tend to work for people.

If you think that working for people is against corporate interests then I think we should just be dine with corporations.

I like people!

It probably depends on the corporations. If a merger would result in all of the union’s employees being laid off, of course the union would fight it.

Depends on the union and the laws under which they operate.

Antitrust law does. That requires a government that cares to enforce the law.