I think it depends on how busy your life is, and how many friends/how big your social life is! - this is probably true, but again, being that busy that basic life becomes stressful is a choice - nobody's making you live like that.
We travel a lot for business and on holidays, so that takes hours to organise.
How does it take hours to organise a holiday or business trip? Surely work are doing the latter anyway?
The bills are automatic but need checking. - I have never done this. I check my bank daily but it takes about 30 seconds on my phone.
Children's dentists/opticians/asthma checks/hair cuts/ - book the dentist when you finish the appointment - opticians can be booked online or it takes minutes to ring once a year. Hair cuts - again, just book once you've done the last one. I accept asthma checks might take a bit longer.
regular clothes checks and replacements - how often are you really needing to do this?
school trips/playdates/birthday parties/presents for family and friends/Holiday activities and plans/school emails/school friends emails/ help with homework/organising sports and hobbies/ remembering the million and one fundraisers/volunteering for the fairs at school etc. - but most of this is voluntary. Your kids don't need loads of play dates, you don't need to volunteer at school or organise loads of hobbies and sports. Holidays are only as stressful as you make them, same with homework.
Yes you can let it all slide, but I don't that is good parenting and detrimental to the children's health, and of course an amazon voucher takes all of 5 seconds but we prefer to send thoughtful gifts. - it's not about "letting it slide" - most of that is work of your own choosing and it's hardly necessary.
We have dogs/cat and two rabbits all need walks/feeding/exercising/ attention.. - again, you chose to have multiple pets! It's a choice not a necessity - don't get them if you don't want to put the work in to care for them.
Then there are house repairs, decorating, organising car insurance/tax/MOTs car repairs and associated recovery services - how often does this come up, really? It takes me about a minute to book my car in for an MOT or service. Insurance and tax are all on auto-pay, same with the breakdown cover.
Checking on line refunds weekly and food shopping is life admin to keep everyone alive. - How many online refunds do you need to check? Surely the food shop is easy online once you've done it a couple of times? Just add all your favourites and delete/add as necessary.
My own long list of smears ( I have them annually) hair apps/pedi and mani/ waxing/opticians/physio for back/gym membership/dentist/teeth cleans etc - oh, come on. Hair apps, manis, pedis, and waxing are all 100% optional, so is the gym. The dentist, physio etc. you just either book as you leave or have a standing appointment, surely?
There is Christmas, which is huge. Birthdays, Easter and Halloween. - these things are only as big as you want them to be. Don't make them "huge" if you're then going to moan about the work?
Then there is the catching up with friends/family making time for everyone. Organising nights out, dinner. 1000s of emails. How does that involve "thousands of e-mails?"
I find it is bloody relentless. It is click on ocado and pay the odd bill, maybe if you have no kids, no pets and a very minimal social life it is like that...but not for me, or any of my friends. - But you're CHOOSING to make your life that way! If you don't want to do all that work - don't. The world won't fall apart because your kids don't do constant activities or have constant playdates, or a "huge" Christmas.