Please educate me. Why cant you get a Mac number if your on cable?
Because it doesn't work like DSL broadband.
Cable broadband is inherently monopolistic because the cable goes back to the operator's local headend.
On the other hand, DSL broadband goes back to your local incumbent telco's exchange. From there, various fancy things can be done to either put you onto an LLU provider, a DSL provider buying wholesale from the incumbent, or indeed the incumbent's own DSL product.