xDSL on the other hand is like a private road just for you and your speed is limited by the condition of the road.
Either you have oversimplified or you are talking rubbish. I will give you the benefit of the doubt and guess you are in the former category, therefore :
For the avoidance of doubt, xDSL is a private road
in the portion of copper that runs between your house and the local telephone exchange.
Once you hit the first piece of active equipment at the local exchange (most likely the DSLAM) , all bets from there onwards are anyone's game. And believe me, the ISPs know that and will take opportunities at every level !
To repeat what I said above :
How else do you think the providers can offer "super fast broadband" at a stupidly low price per month. You get what you pay for. Pay more, you get better broadband.
If you are a home user, and you are paying pittance per month, then irrespective of whether you are on copper, cable or "fibre" ... you will be on a shared medium of some description, and you will be crammed in there amongst a litany of other ISP customers.