OK, so I may get a flaming for this, but I have to pipe up because it's not always someone being intentionally rude/crap. It's not a defence of the OPs friends because I don't know then and they may well just be taking the piss, but bear with me...
So I hugely appreciate anyone, especially those not in my immediate family or locale, remembering my or DCs birthdays. I do my very best to remember other people and their kids, I really do. I have notes in diaries, I even have reminders set up on my phone for some of them, but I have the most tangential, scatty brain imaginable and I just forget, repeatedly, despite all of this. Sometimes I buy cards/presents and just forget to send them, on a daily basis, for months. Sometimes I manage to catch up eg send a big family voucher for a day out for all the birthdays I've forgotten that year with grovelling apologies, and sometimes the gifts lie there, wrapped (or not), being forgotten on a daily basis, occasionally until the kids are too old for them.
I also sometimes forget thank yous (including those I've taken time to make and in some cases even addressed). It really really isn't for want of good intentions or manners. If I was 8yo now I could probably get an ADD diagnosis but I'm not and I don't and I just have to spend my life apologising and feeling guilty.
In my defence, we've also remembered gifts for years for people who don't reciprocate and because I'm quite so shit at this it doesn't bother me at all. I do it because I want to.
It's also not just presents I forget, it's everything: taking unwanted stuff back to shops, posting letters, replying to emails etc etc.
For economic and 'it's all getting a bit out of hand in the present department' a few friends have all decided together than we'll only do kids' birthdays and not Christmas, as they all do perfectly well for gifts. I kind of wish the people who are more together than me would let me off the hook by being a bit more crap sometimes tbh!