I know someone at HP who suddenly had to go in to work. This put him in a situation where he had to pay thousands for day care and he threatened to leave until they finally let him work from home again.
If I found out one of my employees was taking care of his kids while working at home, you better believe it would result in a conversation and a possible revocation of his use of the remote work policy.
Maybe they work better without coworker interruptions and in a familiar space, which offsets any negatives of caregiving.
And even still, who cares?! Do you actually have a good handle on how many of your employees just read HN or Reddit for half a day? Unaccounted for smoke breaks? Having to make personal calls while on the clock?
Humans aren't automatons.
Don't need a handle on it if you block access to them.
But my work found that blocking Reddit/Facebook actually made less work get done: people couldn't spend 5-10 minutes to unwind and then plug back in and work. That policy lasted a single week.
If we generalize that to "what is wrong with frequent distractions" - open plan offices would fall into that category. For an answer, I would direct you to read any one of the many well-articulated anti-Open-plan rants on HN. Toddler care has all the downsides of an open plan office without the (possible) upside of increased team-productivity.
If I found out one of my employees was using their office as a social lounge while working at my company, you better believe it would result in a conversation and possible revocation of their on-site privileges, forcing them to work in solitude at home instead so I could see real results.