Why Dave's Council Tax plan is plain stupid

Another day, another flakey tory policy proposal.
Davey C's floated proposal that Council's should have a referendum if they propose Council Tax raises above a certain %age certainly does sound like its devolving power and decision making right down to the people.
But I think there are two faults with this:
1) The %age trigger rate set by Government will effectively be a cap in all but name. No Council would ever try putting a referendum on higher taxes. Just like the Government doesn't have a referendum on capital punishment.
2) There are quite a lot of voters who don't actually pay council tax, or full rate council tax, either through benefits, exclusions (students, care home residents, monks/nuns) or discounts. Or those who pay council tax, but aren't permanently resident (owners of empty properties, 2nd home owners).
Should these people be excluded from the democratic process?
So nice sounding policy Dave. But another one that when you give it a moments thought is actually quite ridiculous.

Why not come up with a simple policy of scrapping the unfair council tax?