Right out the window

I have to vent. I just don't know about people and thier manners these days! I don't understand how difficult it is to RSVP for an event. It's not like the person has to do anything other than to e-mail, call, or write!
Recently, I've had the amazing (aka heinously stressful) job of planning my sister's bridal shower. I mailed out professionally printed invitations (old fashioned "snail mail") to each event. On the bottom of the invite it was clearly marked 'RSVP by [date]' with a working phone number.

As the date got closer (and the 'RSVP by' date had passed), I wondered why not everyone had responded. We called people up and asked them if they intended on coming to the shower. I got responses such as:
"Oh, I can't attend, I'm working that day."
Ok so how am I suppoed to know this?
"Oh, I really meant to call you but I'm trying to get a babysitter."
A phone call letting me know this would be appreciated!
"Yes, I'm coming. "
I'm not a member of the psychic friends network so how the hell would I have known this?
"Yes, I'm coming and I'm brining a friend and her child"
#$%^& (blood vessels bursting)
ANSWERING MACHINE.
So I leave a VERY NICE messaging asking for a response by x date. Of course none arrives.

What the hell is wrong with people? Where has etiquette gone? Do people realize that brisal showers cost money? We had to provide a headcount in advance. We were charged on that headcount. If more showed up, we were billed more of course.

I came up with a few theories as to why people don't rsvp:

1) They don't know what RSVP means. No excuse in my book. If I were to receive an invitation with four letters on it next to a phone number, even if I didn't know what the letters meant, I'd call that number. The number is there for a reason.
2) They decide they can't go and don't bother to call.
3) They decide they can go and don't bother to call.
4) They plan on RSVP'ing but put it off until later and forget
5) They lose the invitation
6) They are ignorant assholes and plan to show up with their kids unannounced because they are entitled to.

The shower was in March. The bachelorette was in May - same kind of thing. I guess people just don't rsvp anymore. It just annoys me and I needed to vent. Please people -- when you get an invitation RSVP right away! Forgetting is not an option. If you lose the invitation, call the host/hostess of the party. Parties cost money and it's just the courteous thing to do.

There is no excuse!

Ok I feel better.