Witzer, welcome to PPRuNe.
Not just the rate of no show but the reasons as well.
Get hacked off with statements of some that pax have "chosen not to travel with us today" when the real reason is that a number of pax are stuck in the security queue due to security not providing sufficient resources for this. Whose fault is this ?
Then there are terminal gate displays with a notice "pax must be at gate 40 minutes before departure or will be denied boarding", yet are still stating "wait in lounge" at departure time. In a few minutes (or it could be a couple of hours) this will then flip through Gate XX to Final Boarding in short order. Just to aid this process the bulk of the seats in the 'lounge' facing the displays have also been removed so pax will while away the time in the shops instead. Sound familiar, Heathrow T1 management ? There was a time when announcements were made simultaneously with gates being posted. Then this was abandoned. Fine (and probably impractical now) for normal circumstances, still valuable when departures become disorganised.
Then there are the displays which state "Final boarding" at T-40 when the inbound aircraft has not even arrived on stand. Stansted is a constant miscreant here. Regular pax (you know, the ones who make up the bulk of the revenue) eventually get wise to this being a nonsense. Then one day it's a bus gate and the 40 minutes are needed, but the pax are not all there. Whose fault is this ?
Giving out both legs of boarding passes on a day return, and/or OLCI, where the first you know the pax is about is when their BP is collected on boarding, is another source of absence. A telephone number to report being delayed could be printed on the BP, but it is not. Of course whether such a number would ever be answered and/or anything done about it is another matter. And we are all encouraged to use public transport to the airport nowadays, the train running in tunnels out of reach of phone signals.
By the way (speaking of OLCI), Checking In At The Counter, as described in the original post, is regarded by airline management with anathema nowadays. It will soon be OLCI only. What will that do to the no-show figures ?
It's amazing as many pax turn up at the gate as actually do !