As a general rule, our players keep their money stored safely in their bank (BlockBank2) which means they do not have the cash in their wallet to use /jail pay and being in jail means they are not able to run to the ATM. As in real life, somebody on the outside usually has to do the legwork and post their bail.
Suggested command format:
/bail [playerName] - Get the bail amount (as is used for /jail pay)
/bail [playerName] [amount] - Post the bail amount (as is used for /jail pay amount)