sose wrote: Solo, I thought the hosting company sells only space. This will be like a milk in a cup and everyone could brings different sizes of straw to seep, which is the bandwidth in this case.
I'm afraid it is. Just as you and TheBishop described. They have to do this because they also have to pay for that bandwidth to the ISP that they're buying their connection from. And that connection won't be like a single home ADSL, It's probably a leased line implemented using MPLS, framerelay or even a satellite dish. As far as I know, those are usually paid as a fixed monthly or yearly fee. If the web host does not apply monthly bandwidths fees, it has to resolve this cost somewhere, eventually the price of hosting will become higher on everyone, although some websites might be taking far less bandwidth than other websites. This is obviously not fair, and would deter small companies from hosting.
The market for hosting is extremely competitive, so they have to lower their prices, you are almost assured to find a suitable plan if you search enough. I once used a $12 per year host with unlimited bandwidth!!. Of-course it is a low level host, with few features and slow support team, but for a personal website, it does just fine