Meetings require some base level of focus on the meeting, so it is still work. Some people might get away with playing games or reading Twitter or whatever during meetings, but it isn't actually a restful break.

Most meetings are not coding but they are all work. No chance I would be attending without getting paid and by the same token I'd likely get sacked if I failed to attend.

I can't imagine a solo indie dev has those meetings though. So their definition of work is somewhat different.

Also I guess the three hours is a consequence of them having a successful product, which is somewhat akin to winning the lottery. I can't imagine if they were struggling to make rent they'd down tools at 11am for an afternoon of reading and walking.