As theOAP says FBAR is about seeking out criminal activity and this week my son had an "interesting" experience.
My son was called into his bank last week to answer questions about suspicious activity on his account that may be money laundering.
In January I sold our car to the big VW dealer in town a couple of weeks before we left the country, returning to England to live from Texas. The check was $14,000 which is above the $10k mobile check deposit limit and we no longer had a local bricks and mortar place to deposit the check so I went into my son's bank with him and endorsed the check in front of a teller before he deposited it into his account. He chatted with the teller, explaining what we were doing.
He then used Transferwise to send the money into my bank account in England, and to avoid wire charges he sent 3 payments over a 4 or 5 week period using ACH. This resulted in him being called into the bank. Apparently he should have explained to the Teller clearly what he was intending to do, or better still called the Bank as they only saw a large sum being deposited and then paid out in smaller chunks to an overseas bank. This was all easily accounted for, no cash involved and obvious from the deposited check where the money had come from but he was called into the bank for questioning rather than a simple phone call.