This question (or very similar) comes up every few months. And I will say the same thing, as I have said in the past:

You can't wear what you haven't got.

At a wedding where there could be 6, 9, maybe 12 months to plan or save money for a new outfit. Whereas a funeral is a week, 10 days, three weeks tops. There might be no time or money to buy something new and special.

I have seen men, who had been picking strawberries, walk off the fields with mud on their boots and their knees and their hands and follow the hearse. Each and every one of them was no less respectful when they stood in church to mourn a dead collogue as was the Mayor stood beside them in his robes and chain of office.

It is the attitude you wear that makes the difference, not the clothes.

Regards

Chas