Australia and New Zealand operate a no scan no fly rule if selected, with limited exceptions such as documented disabilities preventing the use. They have R&S QPS scanners in at least some locations (the two walls) so you cannot even say you're unable to raise your arms up.

The United Kingdom does allow opt outs but the alternative pat down will be carried out in a private room followed by a wanding, ETD, and hand search of carry ons. Passengers will often be told there will be a wait of up to 30 minutes for staff to become available for the search.