It’s up to the state to figure out details like that.

If a state does install a charger, they might pass a local law that makes it illegal for commercial chargers to operate nearby - which would ensure the state charger doesn’t cost tax payers any money (because a good charger with no competition will run at a profit).

I’m not saying states will do that, but they have the option. The only thing that matters is that there is a charger available, and at competitive prices. I can’t imagine why the state would bother though, because again chargers are profitable and commercial enterprises will want to install them.

Realistically the only thing that might stop a charger from being installed along a stretch of highway is if the government doesn’t allow it due to zoning issues/etc. This law will force governments to ensure there is appropriately zoned land somewhere along the highway.