ScaredyKnickers ALL below are YOUR words, in YOUR post... AND posted in AIBU - which de facto suggests someone wants other's views to 'test the water' around their own - in your case, slightly bitter & resentful sounding; pretty narrow minded (in terms of your comprehension of others); & horribly judgemental - view?
But you really weren't doing that, were you? Is beyond clear from your posts i) that you fancied a rant; ii) that you expected all to agree with you.. and when the majority DIDN'T, you just ignored them and then grabbed a spade to keep digging, adding uber 'judgy' (& a tad peculiar other things like the "we provided" 
to the above just for good measure) YOU:
1 -This has happened a few times now with different parties for my DC where one or two of the invitees have turned without even a card. On one occasion, the parent had not even replied, DC just turned up empty handed. These parents have never struck me as struggling for money and card can cost only 50p anyway. I would never send my DCs to a birthday celebration without a card and a present. Smacks of 'can't be bothered' to me and complete arrogance.
i) As should (by now?) be pretty clear, & from a HUGE number of posters, the fact that These parents have never struck me as struggling for money DOES NOT mean that they AREN"T maybe struggling for money; OR that YOU could POSSIBLY 'KNOW' that or their circs.?
ii) 'Smacks of 'can't be bothered' to me and complete arrogance.' No it doesn't - the ONLYarrogance I've seen on here (setting aside the delightful Wallison for a mo) is your refusal to 'hear' those of whom YOU sought views from? Ditto the arrogance in the implicit 'judging'
2 - Ok then. It seems IABU! Must be projecting my standards onto others!
Trust me hon, you're not
- I have today built a magic force field around me to protect me from EVER having the 'standards' & values
that you seem to have.
Also recently had a small party where we provided an evening meal, cinema trip and did all pick ups and drop offs. 2 DC turned up with nothing.
NO SHIT Scared? SERIOUSLY???! YOU host/throw a party for YOUR DC where you provide whatever the party consists of? Wow - there's a shocker huh?
AND 2 (TWO!!!) of the selfish little shits guests (i.e. children coming to join your child in celebrating their birthday) bring NOTHING? Where were the bouncers when you needed them huh?
3 - Actually my point was more about acknowledging the birthday DC with a card or small gift on THEIR special occasion not just treating it as just a 'free fun activity' Well Scaredy (& strictly entre nous ok?) I should fess up that I am generally verreee big on entrepreneurship... but I think you'll find if your DC's parties were not, err, free (or you poss started charging and it NOT being a 'free fun activity'... err, like a birthday party IS???) then your l'il DCs may find themselves with a pretty lonesome party?
And so, after ALL of that, AND having canvessed over 190 views/opinions/other realities being politely pointed out or suggested to you, you end with this gem:
Still think it's bloody rude and think it's because the parents can't be arsed.
Scaredy - why the f*ck did you even bother asking anyone else then? Ahh, yep.. it'll be all those reasons way up at top - seriously, thanks for the ROFL
, first time have laughed properly in a fair few days
.