"I imagine a hospital that performs surgery via telepresence. This seems a pretty clear area where I would really want the opportunity to pay more, to ensure that the connection between the surgeon and his robot never even suffers the slightest amount of jitter."

This is a common objection, but it's entirely irrelevant to net neutrality (and in fact, net neutrality actually helps here).

Even small hospitals (certainly ones which can afford a robosurgeon) already pay for dedicated Internet connections (often redundant across two or more different providers) to avoid this type of problem. Such connections have guaranteed minimum performance characteristics and are not subject to any kind of throttling on the ISP's part. This is true of most businesses with physical locations.

Net neutrality is more about preventing the selective throttling of services as they come across non-dedicated (e.g. residential) Internet connections. This is where ISPs typically engage in such selective throttling, since they tend to sell maximum instead of minimum performance characteristics (for example: a residential plan might include "up to" 15 Mbps at any given time, while a commercial plan might instead include "at least" 5 Mbps at all times). That maximum is shared between all other residential customers in a given geographic area (e.g. a neighborhood), so selective throttling is employed as a way to keep up the illusion that each residence has its own high-speed Internet.

Put simply: net neutrality does not actually negatively impact businesses (and especially not hospitals), since their Internet plans are not subject to selective throttling. Ensuring that you have enough bandwidth to run your telepresence robot without jitter (beyond making sure that you've purchased a plan with the right bandwidth minimums) is the responsibility of the hospital's own network administrator or equivalent (namely: by prioritizing the robosurgeon's traffic over other less-critical traffic).

Net neutrality does not prevent anyone from choosing to pay for more bandwidth. It only prevents ISPs from being the ones to decide how users allocate the bandwidth for which they pay. Thus, net neutrality would benefit the hospital in this case, since the hospital can decide for itself which traffic should be prioritized within the constraints of its available Internet bandwidth.

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"cell phone provider who wanted to provide a very basic service level that would allow free use of Facebook and a couple of other apps"

The usual problem is when a provider wants to offer Facebook specifically (which is anticompetitive, since it gives Facebook an unfair advantage over, say, Twitter or reddit).

The specific case of which I'm aware was when Facebook itself wanted to offer the sort of plan you're describing, with (unsurprisingly) Facebook being the free site, all under the banner of "but think of the poor people!". If that's not monopolistic, I don't know what is.

The much better approach - if one really does actually care about poor people (I've yet to be convinced that any ISP attempting to justify such practices is actually honest about its motivations here) - would be to just provide slow-speed Internet connections with some high-speed exceptions for specific types of traffic (like audio/video). This is how T-Mobile's non-unlimited plans work, and while net neutrality purists usually object to it, I personally see no problem with it as long as all audio/video providers are treated freely and equally.