Propane - Refills better for environment than exchange
1- Refilling may be done at many service stations, garden/nursery center, etc. This is likely to be closer to your home than an exchange location like blue rhino.
2- Tank exchange is much less environmentally friendly than having your tank refilled. Trucking around a bunch of small blue rhino propane tanks is much less efficient than trucking a big propane refill truck that will fill up your local dealer's big tank, then yours. Think about it - by refilling, you completely eliminate the blue rhino mass refill center too.
3- A tank designed and certified by the government as a 20 lb tank should accept a fill for the full 20 lbs. If you pay for 20 lbs don't get 20 lbs, you are getting ripped off and that company is unscrupulously profiteering out of your wallet. Don't do business with them.