the CPB officers can't really win either way....
I've seen an elderly couple giving the CBP officer a 3-minute speech about
how he wasn't doing his job properly becaue he failed to stamp their passports.
but there are also people who want to keep their passport pages as blank as
possible in order to save a few buck.(not having to add pages or get new
passport)
like I said, no-win situation for the officer.