Why are prepaid carriers so much better then traditional ones, it seems? I've been on Metro for years, service is identical to T-Mobile at a fraction of the cost with no hidden fees.
Competition. You can switch to anyone else easily when it's prepaid with no contract durations getting in the way, so they have to behave well to keep your business. I've been on AT&T prepaid for years at 30/month with only sales tax on top of that.
They are not perfect though - roaming tends to not be available and they can get deprioritized more than the post-paid plans, sometimes painfully so; I was once outside an Ikea trying to notify them to bring out my order and the deprioritization was so bad that I had to walk into the store and use its wifi to notify them to bring out the order. Most prepaid companies are now owned by the primary carriers in the US afaict: Metro by T-Mobile, Visible etc. by Verizon, and Cricket by AT&T, for e.g.