There is nothing Localbitcoins can do to prevent a buyer from charging back on you after you've released the coins. Buyer reputation is a good proxy for safety but it is not a guarantee.
This is why cash is kind when trading BTC, especially on LBC as it is impossible (afaik) to verify that someone is the original owner of the account. You should only accept payment methods that cannot be reversed and as based on cash.
You also need to be able to protect yourself against fraud by taking certain precautions when selling BTC, for example to make sure that the payment has been received prior to releasing escrow.