This used to be true for a promotional period, but they eventually began charging a reload fee usually between $3 and $5. The rechargeable ones also tended to ask for a lot of cc type personal info as well like SSN, address, etc. I used to work customer service and Money Center for Walmart when these cards began getting popular, so I had to troubleshoot them often!
The true gift card CCs ask for no info other than an automated phone or website activation. Basically just like a store gift card but usable anywhere Visa/MC are accepted. Unfortunately the lack of information gathered led to them being used in scams a lot. So if you do end up buying them regularly, the cashier might start to ask questions just to make sure you aren't sending them to any Nigerian princes.