@ANameChangeAgain
I find this very odd and cheeky. I married 25 years ago, and it certainly wasn't a thing then! I've never expected to be fed by employers when I worked in offices, and I've never fed tradespeople in my home either - apart from the obvious coffee and biscuits. If I was a service provider at something as personal as a wedding then I would be taking a packed lunch.
I got married 19 years ago and our photographer did ceremony, group shots, some couple photos, fake cake cut and then left, so about 5 hours. So no need to feed him. Maybe yours was similar?
These days, normal coverage is from about 2-3 hours before the ceremony for bride/ groom prep, through to just after the first dance, some stay later to get more dancefloor shots. It's a long, physical, usually 12-14 hour day with most of that time spent on their feet carrying heavy equipment.
It's not the same as working in an office, where you are sitting at a desk, have access to a fridge, kitchen and hot drinks and can take a lunch break. It's also not the same as being a tradesman in a house, as again, you can take a lunch break at lunch time.
For a wedding photographer, the flow of the day (prep straight into ceremony straight into group shots, candid shots, couple photos, reception room details and set up, couple being called in to meal, sometimes speeches before meal) means they literally can not take a break from bridal prep until the meal (which is usually around 4-6pm), by which point they have worked a full day, skipped lunch and not eaten since they left their house that morning, and have hours left to go.
Wedding venues can be in rural or out of town locations, so it's not always possible to go out and get food, and as others have said, the schedule can often run over or change last minute on the day so it's risky to go offsite. They can't keep food cold in a hot car from 8am until 6pm or lug a cool bag around with all the photography gear, and to be honest, they need one proper hot meal to power them through such a long day.
So, it's not cheeky to ask to be fed one meal, it's just practical. (Doesn't have to be the full wedding breakfast, a bar meal is fine). It's standard practice in the industry for hotels and venues to provide a supplier meal option for photographers, videographers etc.
Hope that helps to explain it.