Brighteyes, what an unpleasant post. Just because you once experienced a family disrupting a flight doesn’t mean that all young children will behave in the same way. It also doesn’t mean that families who travel with young children are being selfish. Family decisions are made with the needs and desires of everyone in the family - yes the 6 month old has no conscious desire to go to Spain, but if the parents want to go, enjoy a relaxing holiday and have time away from work/home then that will be good for the baby too.
We have travelled with our kids since each of them were babies - the youngest had her first (3 hour) flight at 6 weeks old, and each of them had been on 3-7 flights by the age of 2. Occasionally they have cried or been fussy on planes, but we’ve always been well prepared, and they’ve honestly never been disruptive to other passengers for longer than a minute or 2. On one flight to the US I walked around with our then 14 month old so that she wouldn’t disturb others - the cabin crew didn’t think she was being particularly disruptive, but I was hyper aware.
All 3 of our kids are excellent travellers, know how to behave on planes, in queues at passport control etc and to us it seems that it’s at least partly down to having travelled with them from a very young age - it’s not new or surprising or different for them. Good behaviour when travelling is, in the absence of special needs, learned behaviour, and how are children going to learn if they’re not in the situation until they’re older?
You also make unpleasant assumptions about parents who travel wanting to ‘dump’ their kids in childcare. Firstly - not all of us do, in all our holidays our kids have never been in a kids club, and we have only stayed in a hotel a couple of times; villas or apartments are our choice. However I do have friends and family who enjoy staying in resorts with lots of kids’ faciliites - in some cases there are medical reasons why a break from the children is an important part of the holiday, in others the children enjoy and want that kind of holiday.
Finally, what a ridiculous assertion that 5 is the age children can appreciate being abroad - again, my children have very clear memories and fun experiences from a variety of countries, and it’s important to us that they grow up with an appreciation of different cultures, languages, foods etc. Of course, we don’t have to travel to do that, but we’re fortunate to be able to afford to do so. We would have missed out on 9 years’ worth of holidays and experiences if we’d waited till the youngest was 5.