I'm pretty sure someone else might already have said some of this, but it's almost 7am and I've not slept at all for more than 30mins total in the past 5 days, and I'm not going to read 5 pages of replies to check, so apologies if it's already been said.
If someone is WFH and being paid for FT hours (ie 37+hrs), then that's exactly what they should be doing for that number of hours, working on what they're being paid for, in exactly the same way as someone working at their employer's place of business would be expected to do.
If you work 'on site' you couldn't expect your employer to allow you to be doing school drop-offs and pick-ups during your working hours and to pay you for the privilege, or for your kids to be in your presence, wanting/receiving your attention outside school hours and during holidays, so why should those who WFH be allowed to do it?
I can understand if something has been specifically agreed about maybe 30mins morning and afternoon to do the school run, but that time should either be made up within certain parameters that work for the business, or unpaid, but no, just no, when you're working, the kids shouldn't be anywhere near you (unless you're a childminder or some such job).
I'm retired now and my kids are adults themselves, I worked in offices and had to pay for childcare outside school hours and during holidays, and we all used to have something to say about the smokers 'slacking off' for 15mins out of every hour so they could go outside for a 'fag break', whilst the non-smokers carried on working. Those multiples of 15mins soon added up. Think about it, 15mins every hour for let's say 7 hours each day, 5 days a week, that's 8hours 45mins every week, multiply that by say 46 weeks to take account of average-ish A/L and bank holidays, that's 402.5 hours or 53days 5hours or just under 11 weeks per year (based on a 37.5hr week), of lost productivity every year for each and every smoker, whilst the non-smokers are quietly seething about either having to pick up the slack or simply about the smokers getting paid for having all this 'paid' time to have a ciggy and chat!
In theory, it's exactly the same.
This may not be popular, but it's MY opinion.... if you want to smoke, do it on your own time, and if you've got kids, get cover for when they're not in school, everyone else has to do it and work the hours they're paid for, so why should WFHers and, using this example, smokers, get away with it?