that result in an automatic 1st down. It opens up a ton of possibilities where the team with the ball didn't have to earn it based on their execution like an on-sides kick does. It adds a big element of subjectivity (i.e. reffing) that isn't there with on-sides kicks. With an on-sides kick, the receiving team literally can't be called for a penalty, so it means them blowing it is entirely up to execution.