They're back because the they've virtually eradicated the virus there. They don't put up with the anti-everything whiners. Same for New Zealand.
We need vaccines in arms and evidence that it's working to kill off the virus. Unfortunately, we're not going to see that until fall. Might be too late for full stadiums this year.
Hopefully, we can do a social distance Argo model, with few people in the stands this summer. But, nothing like we're seeing in Australia and New Zealand.