Which is not how it works in the rest of the world. Only U.S. consumers are so used to getting screwed that they would defend it as normal. Verizon loves double-billing so much for cell service that they want to do the same with the internet.
Also, your phone provider does get charged for each incoming call. They just eat/redistribute that cost, since for normal phone user it's likely to be less than a penny per month. But try running a conference service and you're definitely going to get billed for incoming calls (apart from some weird force-subsidised areas where you can get paid to receive calls)
I'm pretty sure you can still do this.
From a Singaporean perspective, that's the most bizarre part of mobile service in the US. I need to get an unlimited texting plan so that I don't get billed for people sending me texts? Whoa!