Here's what YOU don't get:
When one works on a G day, and gets a 2.5% of 1 months' basic pay as a bonus. The only reason he is being called is because he will not trigger overtime, or at least costs the company a lot less than the next pilot on the list they would have to use.
Meanwhile, other pilots are strapped to their phones, can't travel, can't make plans, can't drink, can't commit to anything because they are on reserve. But crew control is not calling most pilots on reserve, because those pilots will trigger overtime. While a G day worker might get 2000HKD to spend all day in a plane and a night in a hotel, an R day guy could trigger 3, 5, 10 or 20 times that amount.
Crew control knows almost exactly how many pilots it will take to crew the day, from experience and statistics, with a few spares on hold, but they want to keep a whole bunch of pilots on FREE no-credit reserve, if possible, while using as many pilots on G days as possible, for just the 2.5% (knowing they can call the most junior pilots first go minimize the value of the 2.5%) while R day pilots are kept chained to the phone for free, just in case.
Virtually every time a G day pilots accepts a flight for the 2.5% bonus, it means some R day pilots is missing out on much, much more overtime than that. Then some other day, that G day pilots will have a no-credit R day, but he won't get called out, and he will get no credit or overtime for his R day, because some G day pilot took the bait and screwed the R day pilot out of a much larger payment.
If there are enough R day pilots still available that will not trigger overtime, they will be used first, then G day workers who won't trigger overtime, then R day workers who will trigger overtime, then G day workers who will trigger overtime, then anyone else who will trigger overtime, then the CP or any office pilot or guys in the sim or the DFO himself will go do the flight.
We know that numbers are tight and most R day workers are being called, as they should be, and earn whatever overtime they deserve. That's why we have R day guys.
G day worker: Screws other pilots out of overtime pay while working for very cheap pay.
R day worker: Life is on hold and unpleasant while waiting for call that will not come unless G day pilots avoid answering the phone, and will be screwed out of overtime every time a G day pilot responds to the call because G day guys are only used once all no-cost R day guys have been used.
If there were no G day workers, the company would have to hire enough pilots to roster more R day guys to cover the flights they are used to using G day workers for.
As well, they would rather make 10 no-overtime pilots go to work than pay 1 hour of overtime, causing massive roster disruptions that go on and on. They will also send a cheap G-day worker on a valuable trip (that does not benefit the G day worker) while sending the R day guy to a split duty TPE so that he earns as little credit as possible, or at best even less credit than a post-30-days/year R day credit would have triggered.
All of the above is actively managed and manipulated at much as possible to reduce overall pilot pay...but it is mostly only possible with the cooperation of G day workers.
The company's job is to minimize costs and screw pilots out of their pay.
The PILOTS' job is to work to get paid as much as possible. By sticking together and avoiding G day callout pay, we ALL get paid more over the year. The extremely miniscule amount of money this adds up to in the company's big picture would have no effect on your profit share in the years it is paid at all.
PAY ATTENTION NOW: No G day workers would mean that the exact same number of pilots would be working each day, but with no G day workers, nobody would be paid the tiny G day callout bonus. HOWEVER more pilots would be working on their R days when they expect to and are ready to work, with many more receiving far more rewarding overtime pay which means that EVERYONE gets to keep and enjoy their G days AS WELL AS get and enjoy more money and more G days.