Why are some people so helpless?

How about instead of accusing them, you just offer to teach them.

I usually offer to show them how it's done, and they quickly lose interest when they realize I will not do it for them.
Which is not surprising since they didn't ask how it's done.

For example, I was on my driveway gluing one of my wooden chairs, using a strap to hold the chair together while the glue dries.
A neighbor comes over and asks if I could glue her chairs.
I show her how to glue a chair and offer to lend them my strap and glue.
She turned down my offer.

Do you know how to shoe a horse, or tie a sari?

We learn to do the things that we need. It is pretty easy to milk a yak for people who have spent time around yaks... but many us us wouldn't have the slightest idea what to do with a yak teat.

If people can survive just fine without cooking, why should they bother to learn?

Probably for the same reason your 13 year old asks in a panic before the school bus , Mom, where are my shoes........you answer....Let me see, the last time I wore them....oh my, my where did I leave them. They stop asking.

Then she's got a few choices. She can toss her chairs and get new ones. She can hire someone to fix her old ones. Or she can live with her old ones until they break and she's forced into acting -- and that can mean she jury-rigs hers for a while.

If she wants to live with her chairs held together by rubber bands or whatever, well, she's a big girl and can do that. If she can afford to pay someone to fix them, then someone will get a paying gig out of that, so good for them. Buying new stuff means her old stuff often ends up in a landfill (unless you live in an area where people grab the big stuff out of the trash -- I do, so a lot of stuff like that is recycled. But not sofas or mattresses as there is always the fear of bedbugs). Still, buying new stuff stimulates the economy. Her choice.

But don't do anything for her (or anyone like her) for free. "Sure, Sue," you say, "I can swing over tomorrow after work. Materials will cost $13.80 and let's see, my time will be rounded up to the nearest hour so let's call it $50 for my time. So, $60 total. See ya then!"

I guess that's it. If the task is not a necessity, learning is optional.
They could save a little time if they did it themselves, but it's not enough time to matter.

I would not say that all people are helpless. By himself, a person is lazy and as long as nothing bothers him and does not threaten his life, he will not worry and look for a solution to the problem. But most people can do incredible things. All people are so different, and studying their behavior is so interesting. How many cases do we know when people create such useful things and tame nature.

They may have time as you claim. Then they may not have the energy. Some of it may be due to culture or the way they were raised as you suggested.

At the end of the day, I'm sure they can do some things you cannot do and you don't even know that. What seems trivial (to you or them) or beneath them is there for a reason. That thing does not engage them or energize them. Unless you have specific cases with more information, I've nothing else to add.