You are kidding yourself. The precautions in place make some difference but they're as much for public confidence as for any real belief in the industry that they actually prevent transmission in store. If you stay two metres away from other people at all times, you are unlikely to catch the virus from them... but this is not the case if they cough or sneeze, as has now been proven by a number of scientific studies, and well demonstrated by this modelling:
Meanwhile, the virus can stay alive on a surface for up to 48 hours. Take my bookshop. Unless you imagine that customers can somehow choose books without taking them off the shelves, then every single browsed book could potentially be 'live' for up to 48 hours. Which means, effectively, that at any given time most of the books in the shop will be a potential infection risk, to customers but also to staff who literally spend every second of every day touching books and moving them around. At the till, we are in an area where if we take contactless payment only we might as well not open. Lots of elderly customers who mainly use cash. Lots of wealthy customers who insist on doing things their way and whose custom we will lose very quickly if we tell them no.
The set-up of a bookshop requires most of the floorspace to be filled with tables, with channels for customers to move around in between. Now, we can drastically reduce the number of tables (which will, take my word for it, immediately cost us in terms of takings), but there is still no way for customers to move around the floor without having to get close to one another sometimes. Supermarkets haven't managed to pull it off, and they have aisles! In the summer, when we have steady trade, this is a fairly insurmountable problem. At Christmas, when the shop is normally absolutely packed full of people.. you'd have to reduce customer numbers 100-fold to have any chance of being open safely. And that just wouldn't be worth the overheads.
This is just scraping the surface of the issues. I've barely mentioned staff safety, how to handle the multiple daily deliveries we take, cash handling, customer behaviour, unrealistic requirement for extra staff, etc etc. No-one who works in retail seriously expects to be able to provide a safe environment for staff and customers. It will be a matter of somewhat limiting the risk and then getting on with it in order to keep paying the bills.
A football match with 300 or so professionals of various kinds in a stadium environment under the aegis of organisations with a lot of money, expertise and oversight... the risk is minimal by comparison.