I'd have to agree with most things said here. It's a combination of things.
And yes, people can get very jealous when you don't (have to) work, yet you can stay living under a roof, be it your own or your mother's
Most people move out because they have to or feel they have to. There can be one or multiple reasons why this is the case:
1) They (as Brigand said) would go insane staying with their parents.
2) They feel the urge to be independent, it's natural. A lot of animals leave the nest/home front when they reach a certain age.
3) They have to move out for school, study, work, etc.
4) In order to be able to survive they need income, in order to have income they need to work, which can sometimes lead to point 3 as well.
Since the economic crisis you do see a lot more people staying in with their parents or family members as it is not affordable to live independently, even if they really want to.
It's one thing if someone can't move out, it's another when they seem to actively want to not move out.
However, this all aside, you seem to live together with your mother quite harmoniously. I don't know if you ever spoke to her about your living situation. I know from a lot of people they either are or are not aware their parents want them to move out, but in either case haven't really had much of a discussion with their parents.
Either way, you two seem to have some form of agreement. You two seem to enjoy each other's company, you two also help each other. If your mother needs to go somewhere, you drive her.
Do you also do house chores, cook, clean, etc.?
If yes, awesome! If no, try to do so once every now and again. I'm sure she'd appreciate it. Especially since you're living freely in her place she's paying for. Which includes the house, electricity, water, gas and internet.
You mentioned internet, that everything's for free on there, but in order to get internet you still need to pay for it, which I'm sure your mother is doing too?
It's not critique, but if she does pass away and nothing has been sorted, you might be left with a large amount of debt (and loads of other unsorted things) and doing simple things like going on the internet might not be a possibility anymore.
I'm sure you'll deal with it if she's not around anymore. You'd have to. However, you not only have to deal with her passing (emotional, financially, setting up cremation/funeral, etc. etc.) you'd also have to sort out if you can still live where you are (if that is what you want) or if you can/want/have to live somewhere else. How you would now get enough money to pay for food, water, electricity, and of course internet.
I'm not saying you have to work or you have to start living by yourself. That's not at all what I'm suggesting.
What I'm saying, in short, is that I have no problem with you or how you live.
What I am suggesting is that you figure these things out now, before it's too late. How you're going to deal with these things when she passes away, because that will happen. And she won't be around to help you if you need it.
Find a way (on time) to be able to keep living the way that you are if you want to and that makes you happy/satisfied.