Catholics are bad about tithing. There, I've said it. I don't know how the other denominations compare (excluding Mormon$), beyond an anecdotal story told by my pastor about two parishes, one Catholic and one Protestant--I think it was Methodist--which are situated in the same neighborhood. The Catholic Parish was, I think, St Thomas More's Parish in northwest Austin. In any case, there were about 15,000 registered parishioners at the Catholic parish, and perhaps 1,700 in the Protestant community; the budgets of these two were much more comparable: the Catholic Church's annual budget was approximately $2.5 million, the Protestants $3 million.
My own parish--St Louis King of France in Austin--is itself running a bit of a deficit. We are, according to the finance committee, roughly $90,000 in the hole, and have nothing left in the bank as savings; the parish usually steps up for a weekend whenever this kind of thing happens, but if they don't, we won't make payroll and will have to start laying off staff. The parish has about 5,000 registered families (and roughly 20,000 registered members); and our budget is roughly $3 million/year, which amounts to $12 per family per week collected in donations (5000 families x 52 weeks/year x $12/(family*week) = $3.12 million, for those keeping count). Lest that amount of money seem like plenty, the parish has more-or-less ceased to do maintenance work (for lack of money), which includes both for the church building itself and the parish grounds and buildings, as well as the school; the parish is now looking to lay off staff members and cut what programs it offers, to make up the budget shortfall. And this is a fairly widespread problem in Catholic parishes.
This is why we can't have nice things.