Additionally, the competition will drive down the LN fees. If I don't like my exchange's (or payroll company's) LN fees, I'll switch to an exchange (or payroll company) that has lower fees.
The way the Lightning Network is set up, I think that is already happening. Your wallet will try to find a route from point A to point B which is the cheapest one. Therefore If I offer a cheaper routing fee to the same destination compared to you, there is no reason why someone would use your route instead of mine. Actually, one reason would be if I didn't have enough liquidity in my channel. Someone who has used LN can correct me, but I think the payment routes are chosen automatically by the wallet, based on what is the most cost-effective choice. The sender can't select the route his payment will take or can it?