From my experience, phone plans in the US today are kind of like rent-controlled apartments: The prices for new entrants keep going up, so you have a very stron

From my experience, phone plans in the US today are kind of like rent-controlled apartments: The prices for new entrants keep going up, so you have a very strong disincentive to switch plans. I have a 4-or-so year old plan with a major carrier. I looked in to switching during the most recent round of phone upgrades, and found that my grandfathered plan was at least 15% cheaper than anything on the market that matched my usage. I suspect this is also a major disincentive to leave your parents' plan. Even if you pay the whole bill!