I don't think that council tax should be about income. It is a bill to pay for local services, which cost the same whether you are rich or poor.
Also, who can say what others 'can afford'? It's not all about income - expenditure has to be taken into account too.
IMO, income of any description - inheritance, earned income etc should be taxed more heavily than now, with a higher threshold for starting to pay. This should cover Council Tax, and all other services, and once it has been paid (and rigorously enforced), people should be able to spend their money how they wish - whether that is on a small uniflat or a large mansion.