Students and low earners weren't exempt from poll tax, no one was. In the time it was introduced, I was a student, unemployed and on a low wage at different times and was always going to have to pay 20% of it.
Council tax is levied on residents of a property including tenants in whatever income bracket. Rich renters paying more? No problem at all, but there are also tenants on low incomes living in housing association and council properties which are worth quite a lot because of where they happen to be (for example).
Council tax is also rather stupidly banded - I have some sympathy for people on average income or below living in a house which just happens to be highly banded, but is it fair that the top band CT is only 2.5 times that of the bottom band? I work in an area with a significant number of multi million pound properties.
Last year the newly elected political leadership of my employer - Lib Dem/Tory coalition - decided to freeze the CT. This though was at the expense of many people on the borough who just fell through the means testing safety net (which was established by the Tories by the way) for services. Charges for many social services such as home care and childcare, hitting disabled people, pensioners with modest savings or company pensions (ie above income support) and ordinary working parents (many earning way less than £20K) were subjected to increases of 10-20%. That's what Tory policies mean to me at whatever level of government.
I don't think those of us in the south east pay for worse services - I think many London councils under various political controls actually get quite good services compared to some people in rural areas/small towns. I've come to appreciate what my Labour council does provide and wish that central government, of whatever political shade, would stop attacking local councils in the way that the Labour government has continued to do. And that's not just as a council worker who has to pay council tax (we can be sacked for not doing so or for not paying any other money due to our local authority!) I also say it as a new mum who's discovered what's provided for babies/kids and there's some great services there but the money is unfortunately being cut back (I really missed out on Surestart). And my issues with local government as a service user or wouldbe one don't end with the Tories, council nursery care has gone up 9% this year, making the current rate 50% of my take home pay (which is just over that 25K figure, I don't consider myself poor).