@Ken ******
you've "never understood" which may indicate you have done a reasonable amount of international travelling. What about the first time you travelled? Do you remember checking the stamp to check it was correct? Be honest, and not give an answer to 'save face'. I've travelled outside of my own country on two occasions, 2005 & 2023, in fifty plus years of adult life. On neither occasion did it occur to me to check the stamp. These were 'big' occasions for me and I guess that I was in very unfamiliar 'territory' and a little nervous...making sure that I went to the right place at the airport departure, same at the layover airport, arrive at the destination airport, wonder where I 'need to go from here' (collecting baggage, finding immigration), then standing somewhat nervously in front of a strict looking Immigration Officer, the thought of checking the stamp wasn't even in my thoughts. I'm sure it's the same for many inexperienced travellers.