Money laundering costs money no matter what way they do it.

One of the key signs front line staff are taught to look for in money launderers is a willingness to have lots of expensive transactions (layering). Money launderers are often believed to settle for 50% "clean" money as opposed to 100% unusable "dirty" money.

Can't comment on the logging and anti-fraud tools used by the sites, but as a step in a complicated layering project I don't think they would worry too much. After all, the banks have logging and anti-fraud measures galore but they are heavily (albeit unwillingly) involved in a lot of money laundering.