Santa Clara, CA
said by skuv :The internet itself is "shared" by your definition. It isn't important where the switches are located, as long as the provider has adequate bandwidth to pass the aggregate traffic.
A fiber optic cable isn't a direct connection to the Internet either, so it is shared at some point on the ISP's network before it gets to the Internet. Show me an ISP that has every residential connection connected directly back to their peering router with no aggregation points in between,
My provider, Paxio, offers speeds up to 1Gbps symmetric, and they guarantee you are not impacted by other users on their network. I have the 100M symmetric service and I have never seen any slowdown due to traffic on Paxio's network.
Paxio happens to use fiber to the home, but I agree that twisted pair or coax is perfectly acceptable for 100M users. I would point out, however, that fiber is inherently more "future proof" as WDM and other technologies currently push greater than 14Gbps on a single fiber today.