One thing that they seem to gloss over is that ISP's are not limited by total data transferred (that is an end result from the true limitation of a network which is simultaneous throughput. People pay different amounts for different speeds because that is the true limitation of a network (so you pay more for a larger pipe on your end) Limitations like transfer caps are simply indirect ways of blocking content, for example if an ISP did not have the network capacity to deliver on what it is selling, then they can discourage the use of any service that will actually make use of the fast speeds they are paying for (if it means that they will blow through their cap in a few minutes)
A straw-man argument that they used was the metered use of electricity. Electricity is a lot different from data, and on top of that, the electricity company does not throttle you. I have a 200 amp breaker, and I can pull 200 amps 24/7 if I wanted to (though it would cost a lot), and if I wanted, I can install a 600 amp breaker and pull 600 amps 24/7 with no problem (though I would end up with a bill that would put the national debt to shame)
Electricity and data are handled in 2 completely different ways because they carry a completely different set of challenges.
If an ISP is going to sell a specific speed, then it is up to them, and their cost of business to make sure that their network can deliver that speed at all times. the only bottleneck in the network should be the endpoint bottlenecks, e.g., if I have a 20mbit connection then my max speed will be 20 megabits per second.
Many ISP owners like his want the fast lane because it will legitimize an extremely consumer unfriendly business practice that will be very profitable. For example, even if they are not allowed to throttle, there is nothing barring them from letting the network become congested. This creates a business practice where they can simply prioritize the traffic going to the companies that pay them.
Think of it like this. Imagine a 6 lane road with so many cars on it that traffic is moving insanely slow (e.g., rush hour when cars are going 15MPH on a 65MPH road). Without fast lane the ISP would be forced to add more lanes to improve the traffic. With the fast lane, it suddenly becomes more profitable to take 3 of the lanes and say "hey these banks are paying us lots of money, so you are only allowed to use these 3 lanes if you are heading to the bank, for everything else, you must use one of the remaining 3 lanes" This allows people going to the bank to enjoy very good speeds right up to the speed limit, while everyone going to non bank locations will end up going twice as slow. The cost of maintaining the road did not increase ad they did not expand on it, and they get extra income by reserving the lanes. If an ISP wants to charge based on data transferred, then do not cap my speeds, if I install a 40 gigabit ethernet adapter, then let me download at 40 gigabit/s, but if they are going to sell speed tiers, then the cost is already covered, as everyone is already paying their share, (par less for a slow connection, and pay more for a fast one.
(In my area, when the apartment complex were being built, the power company upgraded the electrical lines and facilities in the area to meat the demand of multiple apartment buildings. (reason being, the added customers would more than cover the cost of the upgrade (not sure if the city was involved with the upgrade or not) but to meet the new demand, they upgraded the infrastructure).
all in all, it is the ISP's job to provide customers access to the content they want. The servers/ producers pay for an internet connection, and residential customers pay for internet connections, it is each ISP's responsibility to make sure their own networks are able to handle the load (and making sure the interconnect is able to handle it (by sharing the cost. e.g., if customers from ISP A want content from servers on ISP B, and the interconnect cannot handle the load, then each ISP on their end will swap out the gigabit switch for a 10 gigabit switch, or even install a 40 gigabit switch (because they have customers on both sides of that peering port demanding use of it.