I am a Cub leader. Just to cover a few things...
I often take my "wrong age" child with me. Not so much now they are older, but younger DD did a whole extra 18 months in Beavers as she started at 4. (Then Covid hit, so the last time she actually went she was still 6 then returned a Cub). This only works if the ages are slightly out.
You definitely don't need to have kids. DH has been a leader since he was 18! Above DD actually did her first Scout camp at 3 months old (day time only) as I helped with cooking.
Ratios... there are different ratios home and away. Its 1:12 +1 for Cubs away from your meeting place for example. We do have 3 leaders for 24 Cubs at home, but it means one of us can be ill without calling in reinforcements.
In our Group we currently have 5 leaders plus GSL. We make up our numbers for camps with other Scout DBSed adults from the Committee. We have 20 Scouts, 24 Cubs, 24 Beavers. So for a camp, that's 3 leaders for Beavers, 2 for Cubs, 1 for the Scouts and 1 in charge so technically we are in ratio. But its very tight and exhausting! We are not even looking at opening a Squirrrels section anytime soon.
Personally I am now counting the weeks until younger DD turns 10 and can go to Scouts. I hate being her leader. She's very silly towards me that she isn't to the other leaders. I fully understand why parents don't want to volunteer with their own children
Squirrels... thats another bone of contention. When so many groups are struggling, why open a section requiring 3 additional adults?
Overall... I love it. I hope our group continues to flourish when our two mid 70s leaders decide to retire.