Hmm. I actually do think it is unfair that someone young is expected to live on less than someone older. If it costs x to feed a 30 year old, then it costs x to feed a 20 year old. If someone meets the criteria for benefits, then they should get enough to live on.
However, refusing to travel more than a 10 mile radius doesn't seem reasonable - yes, even without a car. As someone who spends well over 2 hours a day commuting to work, I don't have much sympathy with someone only wanting to work on their doorstep.
Also, I live in the south of england, and plenty of couples here share a room in a flatshare because they can't afford a flat of their own, and they share the bathroom and kitchen with other tenants. The "rent a room" type landlords don't usually ask for mammoth deposits, letting agent fees etc. When I first moved down here I lived in a granny annexe. It wasn't the lap of luxury (in fact it was hideous), but it was fully furnished, only 1 weeks deposit and 1 weeks rent in advance needed. It let me move from north to south to get a job - I was in the same situation as you, and didn't have a bean (or a partner!).
If you really want to make this work, you can - but you have to stop blaming society and take action for your own life. So, my advice is move to a city where there are lots of jobs (in the sort of places I've mentioned), or be prepared to set the alarm for 5am like lots of do so you can commute.
Or, as someone else suggested, live-in jobs - mothers help, housekeeper, working in a holiday park, helping on a farm or an animal sanctuary, some restaurant/pub work, hotel work all often offer accommodation. Sometimes a caravan on site (farms and sanctuaries) or in staff accommodation. The accommodation will be basic (I spent a summer working for Butlins years ago), but you will be able to save what you earn.