I see what you're saying. I'd say the petty part there is the tallying the small items I offered to you in my home.

Going out to a restaurant with a group is not the same thing, though. If there are three people eating at a moderately priced restaurant and one person picks up the tab, it's not petty to request reimbursement.

In a cash world, it would be petty to demand exact change because of the extra effort it requires to produce it. In an automatic payments world, it's no extra effort on either side.