The thing I'm still a bit confused about is: is this a limitation with how their networks fundamentally work, or an artefact of my product choice when I buy a r

The thing I'm still a bit confused about is: is this a limitation with how their networks fundamentally work, or an artefact of my product choice when I buy a relatively cheap home Internet service? i.e. if I want a specialist low-latency and low-jitter link, could I not just pay for those benefits by purchasing a business-grade service? Or is there no distinction once the data gets onto a peered-network? Or is the idea here that I don't have to cough up for all the benefits of that superior product when I only want some of them and only some of the time? And this whole thing does rely on the bottleneck not being at then edge, which I don't see any proof of or reason for. EDIT: is there any proof/data to support this?