I can't get my head around how my 70 year old dad can play golf with his friends, but my 6 year old can't play with his.
While I get the reasoning behind it from a social distancing perspective, I totally get your frustration and sadness. Lockdown is tough on all children, but I think particularly for only children (or those with a big age gap between them and their siblings).
My 8 year old hasn't played with another child for 10 weeks. Other than Facetime, which he struggles with, the closest he gets is looking through the window and seeing the two children next door playing in their garden. DH and I play with him as much as we can, but he's really missing other children. And he'd love to go to a playground rather than just walk or scoot about.