UPS and Fedex do not allow large customers to pay to delay the packages from smaller competing customers. They also do not compete with their own customers creating an incentive to provide poor service to them in favor of their own products.
What is going to happen is exactly what happened with AT&T and me a couple years ago. They started blocking IPv6 tunnels immediately after adding IPv6 as a service to pay extra for. When I say tunnels, I mean exactly that; they blocked protocol 41 tunnels to other companies which provided free or pay for IPv6 tunnel endpoints in favor of their own pay for "upgrades" to provide the same service. They had all kinds of excuses including:
1. Blocking IPv6 tunnels was required by law enforcement. I sort of believe this one in connection with CALEA.
2. Otherwise customers can use IPv6 tunnels to get static IP addresses without paying.
3. We block IPv6 tunnels to prevent hacking of our network.
4. Nobody provides IPv6 tunnel services.
5. IPv6 tunnel services are obsolete.
I complained to the FCC and they went back and forth with AT&T a few times and then said it was fine.
I think here you are keying in on why Google and the likes (giant app companies) support "Net Neutrality" while ATT and their likes (giant ISP companies) fought it. Why should giant ISPs be constrained as "common carrier" and giant app companies are not? In my view, that is why the giant app companies are paying politicians big bucks to support "Net Neutrality" so they put their potential competitor under maximum constrain - So they remain the sole master capable of such manipulation.
Google using its monopoly power to suppress or at least depreciate competing entities is a well discussed issue. To quote Jonathan P. Allen's book (Technology and Inequality: Concentrated Wealth in a Digital World): "Many of Google's battles with regulators have focused on whether Google misused their 'monopoly power' to highlight their own services in search results." News today are filled with articles on how Facebook uses its power to influence policies and politics by highlighting some while un-highlighting others.
To fix the issue of these guys "creating an incentive to provide poor service to them in favor of their own products", we have to fix it via the Sherman Act and break up these giant monopolies - both giant app companies and giant ISPs.
Re: "UPS and Fedex do not allow large customers to pay to delay the packages from smaller competing customers" - If that happens, that would be anti-competitive behavior that is against FTC (Federal Trade Commission) rules. How companies deal with customers (or each other) is a trade issue falling under FTC jurisdiction and not a communication issue under FCC. Such anti competitive behavior will be big fine and possibly big house (jail).
Your point about tunneling is a more difficult issue. AT&T (and other mobile ISPs) also prevent customer in using a cell phone as a hot spot readily. They would like to see each device having their own paid line under a main account. I too would like to see it being "free to use the pipe to send whatever I see fit." But from a free market stand point, this is what they are selling, and if I don't like it, I should not buy from them.
This may seem unrelated, but it is related. I was considering a trip to Washington DC to attend some kid related multi-day event thing. I cannot rent a hotel room for a single adult male and have my wife and kid packed in the room - even while we don't mind being cramp. I paid for the room and I should be able to use it for what I want as long as what I am doing is legal, right? Instead, I have to pay for a double (me & my-wife) plus another room for my almost adult kit. Their house, their rule! So, seller controlling how their asset can be used is not really unusual.
If ISP's are legally restricted from controlling want you can send through their pipe, should Google/Facebook/Tweeter also be legal restricted from controlling what you put there? I have no good answer for that. Imagining what good things can happen when we are free from such restriction is joyful. But imagining the bad that could happen is mind numbing.