Married at first sight - why do the couples say ‘I do’ at their weddings?

I was amazed when I attended a wedding when on holiday in USA. It was my cousin's work colleague .
It was a most casual affair with the actual formal exchange of vows bit lasting about 2 minutes and not being that formal!
Is this usual US grans?

but in the keys example, both forms of reply are correct, i do have them, is a fuller or more emphatic form of, i have them.

Maybe the wording has been adjusted so as to not be fully lawful and legally binding? I have seen this happen before on the 'Dont tell the bride' TV programme, and can also be part of a civil ceremony where a couple choose their own vows and to marry at a venue without a Wedding license, choosing to make the Marriage legal by visiting the local registery office as a couple a few days after their big day celebrations.

Dh irritates me on a daily basis since whenever I say, ‘Have you got (e.g.) your keys?’ he says, ‘I do,’ instead of ‘I have’!

I don’t say anything though - my inner pedant keeps quiet at home!

I think it's a bit of Americanism creeping in ?
Depends on how it's worded- I notice that in the States the question is "Do you promise?" which of course would have the response "I do"
Whereas elsewhere it's "Will you ?"
You're not the only one that it annoys!

I noticed the same discrepancy in some of the ceremonies. I think some of the celebrants changed their wording but the couples were primed to say 'I do' whatever the question, along with the required long hesitation for a bit of suspense!.
I think it was stated at the end of the Australian version that the ceremonies were not legally binding, whereas in the USA they were, needing a divorce to dissolve them. However, this was also the case in those couplings which weren't consummated. I thought these could be anulled. All a bit confusing.

But Imthought the original wording was Wilt thou? Or Will you? Hence I will

It may be Scots usage, but if anyone asked me a question beginning with "Do you" as in "Do you know Mrs McPherson?" I would be just as likely to answer, "Yes, I do." or " I do, yes." as simply saying, "Yes"

Certainly, if the questioner placed emphasis on Do you,,,. I would anwser I do and not yes.

At the time the marriage service was written in the book of Common Prayer "I do" was considered more affirmative than "Yes".

As others have pointed out the wording was "Do you take NN to be your lawfully wedded husband?" making the correct answer " I do,"

Probably came from America with such phrases as “Can I get”

Sounds correct!

When I got married (1977) the couple (we) said "I will" and my father said "I do" when asked "Who gives this woman..."

I don’t really mind which form of answer is used as long as it matches the question!
Plenty of TV rubbish being watched during these weird, dull tones. Draw the line at the Australian version of this show. And Selling Sunset (Netflix if you’re interested!)

The reply to ‘wilt thou’ back in the early 70’s when I married was definitely, ‘I will’.

I've never watched the programme but I found your question interesting and it sent me scurrying off to the Internet.

My recollection of my marriage vows was being asked Do you Illte take this man.... to which I answered "I do".

Things seem to have changed now with a move away from the old wording to "Will you Illte....."

However, looking at the Book of Common Prayer (1559) I see the phrasing was "Wilt thou.."

So where the "Do you" "I do" came from don't know. And yet it must have been the common parlance at one point for it to have stuck as saying I do.

Well that's my intellectual pursuit for the day. More interesting than cleaning the shower. Thanks?

I thought people said "I will" now - my DDs did.

Please do not waste your life watching this rubbish!