Otherwise, everyone would at least try to scam everyone else and would at least try to become a monopoly, since it costs nothing unless you win. And if you do win, the fine won't reach the amount you put in the bank (at least in the case of monopolies, e.g Microsoft).
This argument might be better applied to what is going on with Hatchet right now.
I suspect Amazon is on their way to running afoul of such laws, or would be if the current business climate wasn't comparatively hostile to the notion of this kind of regulation. I don't think, however, that Zocalo is going to be a piece that attracts much attention; it's going to be the way Amazon seems to increasingly deal with their suppliers in Walmart-esque fashion. (Walmart was notorious for going beyond merely asking for "large customer" discounts and heading into "we will tell you what wholesale price we're going to pay, and you will either make it work or you'll lose the 60-70% of your business we represent.")