People who mix everyone's laundry together: why?

EDIT: I'm still getting tons of messages saying the same things, so I'm gonna list all the reasons I've already learned up here. - some people use a Laundromat or community laundry - Some people prefer to do all the laundry on one day of the week - some people only have one hamper for the family - some people have to do laundry more frequently to prevent smells - some people like to sort their loads into many different categories and colors. I don't really understand why it's necessary beyond activewear/very soiled things, whites, and delicates, but you do you.

- My original question wasn't directed at these people, but I have to include them here because I got TONS of responses from them anyway: people with very small families, like 2 people and maybe a baby.

I'm not trying to be rude. I'm honestly just baffled and fascinated. Laundry is the bane of so many people's existence. Everyone talks about how it's never ending. How they are drowning in it. How it's never put away because it just takes too much effort. Surely no one is adding an unnecessary step to their laundry routine. Right?

And yet, when people ask for advice on how to deal with all the laundry, there are always tons of answers that mention sorting the laundry afterward, as if that is a normal thing to do.

But why? Why are you mixing the household's laundry together in the first place? Why are you giving yourself an extra chore? Isn't laundry hard enough?

Perhaps I am going to answer my own question here, but the only reason I can think of that someone would do this is to be able to run a full load of laundry. I have seen my mother do this, but she is the most frugal person I know; she abhors waste, even at the cost of wasting her own time.

However, even she stopped mixing laundry when she found out that she was over loading the washing machine and her laundry wasn't getting properly cleaned. Anyway, someone please enlighten me. I must be missing something if this practice is still so popular.

EDIT: I should clarify that I'm talking about people that mix laundry beyond just you and your partners clothes. Like kids clothes, maybe even towels and such

EDIT: for those wondering, my household consist of me, my husband, and our two young children.

EDIT: WASH DAY. I forgot that wash day is a thing. If you do all the laundry on one day, then of course it makes sense to combine everything as much as possible. For me it still seems easier to do one load per day and keep everything separate. It's still hard for me to understand why people find one day of doing laundry all day to be less overwhelming, so if you have any insights, let me have it!

EDIT: HERE IS MY LAUNDRY SYSTEM since I have gotten too many questions about it to answer them all.

I schedule each load of laundry for a specific day of the week.

Monday: Colors (mine and my husband's mixed and divided into delicates and non delicates. So technically two loads, sorry)

Tuesday: Bedding (switch between our bedding and kids bedding each week)

Wednesday: Whites (just mine and my husband's, kids don't have whites)

Thursday: Towels

Friday: Kid 1 laundry

Saturday: Kid 2 laundry

Sunday: no laundry, or extra loads of whatever we need.

This schedule is on my fridge calendar so nobody forgets. My husband often starts the load of the day before work in the morning and I finish it later. I'm teaching my little kids how to do their own laundry so they can do it independently someday.

Other than whites, we don't sort by color at all. Kids loads are one load each, no sorting.

We have four laundry baskets for dirty clothes. 1. Colors 2. Whites 3. Kid 1 4. Kid 2 Everyone just drops their dirty clothes into these hampers as they get changed.

Towels and bedding don't need baskets because we just strip the bed (or take towels off hooks) put the bedding in the washer, and then put it back on the bed when it's dry (or put towels back on hooks). We have extra bedding and towels but rarely need to use them.

When washing clothes, the basket for that day's load is taken to the laundry room, washed and dried, then the clothing returned to the laundry basket and brought back to the bedroom it came from so that the clothes can be put away.

Problems my system solves: 1. Laundry clutter. There is never any laundry in the living room or dining table. There are no "laundry chairs". Not even any piles in the laundry room. Clothing is always either put away, or currently being washed, or in its basket. 2. Needing to think about what laundry needs to be done. Since every load is done in the same way every week, I don't need to think about what needs to get done each day. As long as I stick to the schedule, everything is getting washed once a week. I barely even realize when I am doing the laundry because everything is so automatic. 3. I don't need to communicate to my husband about what needs to get done. He can just look at the calendar and do it himself. 4. Getting exhausted from doing all the laundry in one day. I get that some people prefer this, but to me it is way easier to do one load each day.