Comment by indubitable

Without expressing an opinion one way or the other, the reason is very simple to explain. Taxes are seen as taking something away from you. Benefits by contrast are something that somebody else is giving to you. Having less taken away from you is going to be seen as less of an issue than somebody else taking more from other people than they 'deserve.'

There's plenty of lost nuance in this view, but if you try to empathize with people who feel this way - it's not hard.