Everyday we are all near and interact with our family members and we do not have second thought about hugging them, kissing them sitting with them, eating with them, sleeping with them and so many other things we do together. This is true for a disciplined football program. They are a family that works out together, practices together, eats together, socializes with each other and etc. without giving it a second thought.
When my daughter (who works in a hospital outside Chicago - yes she has treated COVID patients), my son-in-law, and 2 grandsons traveled to SC for a visit in July, I did not give it a second thought of being with them and doing all that families do. Why, because I trust them and knew they wouldn't knowingly bring the virus with them because they were following the requirements and being safe. The same is true for an opponent in football. The teams have to follow protocols and when they send a team on the field, you have to trust that to the best of their knowledge, no player is infected.
Like a family with no coronavirus interacting CANNOT spread a disease they don't have and the same is true for 2 football teams playing a game. They cannot spread something they don't have!
Football players are not family members.They come in contact with other people outside immediate family.They do not know who is safe,or not. You obviously didn't think this one out.