It does seem that there is a disproportionate amount of criticism for this particyular layout becaue it is P4. There were a number of other layouts where the running was less than perfect involving finger poking to get things moveing and other faults. Thes don''t seeem to have attracted the same amount of comment.
I was involved with a P4 layout at bracknell and whilst there were a couple of derailments the offending vehicles were removed and checked. On the positive side all of the locos started when power was applied and none of them required poking to get them to move. With any exhibition layout you are always subject to environmental factors. This along with putting in a vehicle and bouncing it down motorways is always chancing something going wrong. It is easy to get perfect running on a regular basis with a layout that never leaves home as it removes most of the facrors that cause problems.
I should think that all exhibitors of layouts would want perfect running for the duration of the exhibition but sometimes other factors get in the way.