You sure about that? Look up Visible, Mint Mobile, Total Wireless, US Mobile, Tello... Same carrier networks, same quality of service. You can even pay a bit extra for prioritized data and other fancy features. You can get basic unlimited plans for $15-30 and premium plans in the $30-50 range vs $100+ at the big carriers. The only difference is that you aren't paying for your "free" phone.
In this case you’ve switched providers, though. Might be a good idea but doesn’t say anything about whether, e.g., ATT will lower your price if you bring your own phone.
I’ve read that these virtual networks also get lower prioritization so you can get low bandwidth when the higher tier users are active. Not sure how accurate that is.
And if you don’t use a lot of data, at least US Mobile has a by the gig plan. My family has three phones on it for a total $30 per month. Those months that we go over, it automatically charges $2 for each extra GB, with data pooled between the lines.
It is easy to switch between Verizon, AT&T, and T-Mobile as well. This was helpful for me as all three of the networks normally have one bar or less at my house. T-mobile WiFi calling works more reliably than Verizon.
Yeah, I got screwed by both Sprint and Verizon in turn back in the day, so for ages I've just done T Mobile's prepaid plan with an unlocked phone.
Works great, no particular coverage issues, never used enough data to hit any notable throttling.