My son got a concussion playing soccer and didn't tell anyone about his acute symptoms at the time. Just kept playing.Thankfully he was never interested, but I would not have let my son play football. I enjoyed it, but also walked away with a not-insignificant neck injury and a lifetime of back issues that are almost certainly related to one degree or another. It is not a healthy sport, period.
Everyone on the team had done baseline cognitive assessment, so they could evaluate injuries, but if the kids don't admit they've had a blow to the head, it's not much help. It's not always obvious to the coach or refs when it happens.