I asked my daughter's best friend who is a public health statistician and apparantly the reasoning for the government not cancelling sports stadium events is as follows.
If you attend a professional sport event you connect with on average 14 people. 6 people who you brush past en route to/from the game. The two people you sit next to, 3 people behind you and 3 people in front of you and the 3 people behind you can only be infectious to you. You are outside for the most part, so less infectious than indoors.
In comparison standing outside like the fans of PSG did is lethal. Watching sport in a pub is even worse as you are in an enclosed atmosphere with 25+ people.
No, the only reason for cancelling sport is if the players can spread it to each other or the use of umpteen police and emergency personal staff who can be better employed elsewhere.