In theory at least it’s because you pay for a specific bandwidth for home internet (the size of the pipe) but a specific amount of data for cellular (how much stuff you can get through a fixed sized pipe).
Home internet is a little unique in that way, almost all other utilities are consumption based with no real tiers in terms of how it’s delivered (you pay for the volume of water or gas you use, electricity is the same, just different units).
Networking equipment gets more expensive based on the bandwidth it supports, but it doesn’t much care how many bits you push through it. So ISPs charge based on their capacity to deliver those bits, and provide tiers at different price points. Cellular though is much more bandwidth constrained due to the technologies (and it used to be much more so before LTE and 5G), so it didn’t makes sense to charge you for slow or slower tiers. Instead the limiting factor is the capacity of a tower so by limiting data to small amounts it naturally discourages use. That model carried forward even now that the technologies support broadband speeds in some cases. As such and ISP could provide the biggest pipe (highest speed) to all homes and just charge based on consumption (they used to in the days of dial up, and satellite before starlink always has). Many ISPs instead are now double dipping though and charging for both.
So we did exactly this when we dropped our Prime membership a few years ago as part of working against Amazon building a massive warehouse in our fully residential borough (we won if anyone was wondering, they chose not to continue fighting it in court). We shop mostly in store at Target and other brick and mortar stores. We will also shop online still, but almost always directly from the manufacturer. This usually means paying shipping, but I figure our UPS driver and mail person need a paycheck too so we are fine with that. We will occasionally use Amazon for things that are just hard to find elsewhere but only order once our cart is in the free shipping price range. It turns out, Amazon is not only a shit company the uses dark patterns to push a mostly superfluous subscription, most things we buy are cheaper elsewhere. Combined with not buying nearly as much random crap, we have saved a butt load since quitting Amazon.