Tv and Radio public information ads

Over the past few months there have been adverts on both TV and Radio encouraging people not to suffer in silence.
The first was for screening potential bowel cancer, the latest is for potential lung cancer.
The adverts have said make an appointment to see your GP (for USA readers family doctor).  Fair enough, but I can't help thinking the makers of the adverts have private GPs, because our GPs are some of the most overworked people around.  If I need a routine appointment, I can wait for up to four weeks.  In the area where I live there are too many residents/GP and it is that fact the causes the long waits. There are also a lot of people who make appointments with the GP and don't turn up, or turn up too late.
I used to work for a dentist and appreciate what sort of chaos late patients can create.  The person who turns up late always has a valid...to them...reason for being late, and many seemed to be blithely unaware they were causing problems by being late.  Although it can frustrate me if I am late in for my appointment, I know this and other factors can be at work. At the dentists a simple filling might become a root filling, similarly a doctor might think that his patient has a routine problem and it can turn out to be much more in depth. 
What we need to do is make sure we are early or on time for appointments, and the government needs to be more realistic with their "public information" adverts.