Never had Customs scan and look at my passport anywhere - Europe, USA or Asia. Not once.
However, Immigration always scan and read my passport
Haha I have had customs scanning my passport once while I was crossing via land from Ukraine over to Poland. Before the passport control to enter Poland there were customs officers wanting to see your passport. They scanned it on a machine they had and wanted to see into my backpack etc. After that was the actual passport control. I am a Norwegian citizen so I went with the EU/EEA line. I have never seen such strict measures at any European border (yeah I know Poland is EU and Schengen while Ukraine is not) so they are probably after smugglers and illegal immigrants I guess. Eastern part of Poland and western part of Ukraine both have very harsh economic conditions. In the Polish border area many folks sell booze, cigarettes etc all smuggled over from Ukraine (booze is cheap in Poland, but even cheaper in Ukraine).