The logic is clear enough, however, to suspect its existence. This is true especially when it happens repeatedly during the year. If they had their way, money and things spiritual would not mix at all. Second thoughts, of course, must modify that ideal. Utility bills, and others, must be paid.
Symbolism is a factor too.
What is put into the collection basket can be seen as gifts of substance that in one sense parallel the spiritual offering of the priest. Ideally, such donations are sincere. Cynics might see them differently, however, perhaps with some justification. Whether conscience, upbringing, habit or keen sense of justice is dominant, all are likely involved. Parishioners know that church needs exist, and that they should do their part to help meet them.