I believe I subconsciously transitioned from “excuse me” to “sorry” (not “I’m sorry”), simply because it’s one less syllable and I’m lazy. Of course, when sarcasm is warranted I still do the [Steve Martin] excuuuuuse meeeee! [/Steve Martin]. Maybe that dates me.
For that extra touch, you can also always go with excuuuuuse meeee, princess! (maybe that dates me, too)
I’m a Midwesterner. “I’m sorry” is engrained in me. I have actually said “I’m sorry, but you’re standing on my foot”.
Excuse me might be used for something like excuse me ma’am, you dropped a sock when I’m at the laundromat.
I say “sorry” when I almost collide with someone, typically while rounding a corner (happens fairly regularly at work).
What I’m sorry for is not paying closer attention to where I am going. I think that’s legit.
mmm
Or if you speak Yiddish:
Yankel: Nu?
Moishe: Nu!
Yankel: NUUU?!
Moishe. Nu…
Californian:
Chet: Dude?
Rand: Dude.
Chet: DUDE!
Rand: sigh, shakes head, Dude.
Also biker:
Rat: FUCK!
Blade: da fuck?
Rat: fuckin’ fuckety fuck.
Blade: shugs. Fuck.
Exactly the same for me, word for word.
What bugs me is saying “I’m sorry” when you mean “I’m sorry I didn’t hear that, would you mind repeating it.”
I keep trying to remember to do that. It’s a social lubricant as effective as 3in1 Oil.
This is the most common use of “I’m sorry” that I make.
The one I’ve noticed more frequently lately - especially with younger people - is to respond to questions with “Don’t worry abut it.” Which we have come to interpret as, “None of your business!” 
I tend towards the pedantic stick-in-the-mud end of the spectrum, but gotta admit I’ve never really differentiated between “I’m sorry,” “Excuse me,” or even “Pardon.” Nor have I ever particularly believed folk saying either are either sorry or desire to be excused. ;). Depending on the situation, any of them mean anything from, “Please repeat yourself” to “Get out of my way.”
Around here they say “Please?”. And not always sounding like a question. Took me a while to get used to that.
Sometimes “pardon me” can be effective in tough situations. A while back I had a little urinal mishap in the men’s room of a biker bar. I accidentally sprayed the fellow relieving himself in the adjacent urinal. Well, this large biker dude took offense to that. He wiped the urine from his face, turned toward me, drew back his fist and was about to swing. But, I said “pardon me.” He relaxed instantly and replied, “no problem, bro.”
Perhaps all these “victims” of police violence could learn a thing or two from your impeccable sense of etiquette. “Pardon me, officer, this is just a cell phone”, “Pardon me officer, would you be so kind as to remove your knee from my neck” and a lot of unpleasantness might be avoided.
I make a specific distinction in usage.
“Excuse me” or “pardon me” are for when I’m doing something necessary or unavoidable that will inconvenience someone or cause discomfort. I hope they will excuse the action, but I’m not apologetic about it, because I could not reasonably avoid it. “Sorry”/“I’m sorry” is for when I’ve unnecessarily caused inconvenience or discomfort by accident or through inattention. In that case, I’m actually sorry for it.
However, it doesn’t matter a whit to me if other people use the phrases differently.
Yup, that’s what the world does.
I used to be “with it.” Then they changed what “it” was. Now what I’m “with” isn’t “it,” and what’s “it” seems weird and scary. It’ll happen to you! -Abe Simpson
As I approach the once-terrifying spectre of middle age, I look at and remember older folks I’ve known. None of them managed to stay as current on fashion, entertainment, and slang as they had when they were younger. But I see a distinct split emerging between those who remain curious and those who resist change, and between those who can laugh about it, and those who are upset at being left behind. That part, to me, seems like a choice.
In the Good Olde Days, people said “I beg your pardon” or “I am sorry” (never “I’m sorry”) if you said or did something they found offensive or impolite. Always in a voice dripping of icicles that would turn Liquid Oxygen solid.
Nitpick: They’re not platitudes, they’re phatic expressions.
Brilliant, I love it!
sorry (or excuse me?), I guess I am entering zombie territory, but this reminded me of one of my all-time favorite TV scenes, which I just had to share
(warning, the Youtube video is NSFW)