Captain I think you are mistaking the idea of a PPL. A PPL is for private flying. It also allows a pilot to fly on personal business, though the cost must be borne by the individual, at least on an equal basis with everyone on board. If you wish to fly beyond the privileges of a PPL, or beyond your capabilities at licence issue (and it is to your great credit that you recognise that the capabilities of a new PPL holder are more restricting than the statutary limitations of licence privileges) then you can pay for extra training. I know no schools that would refuse to provide some. On the other hand someone who simply wants to fly to the Isle of Wight every couple of weeks (as one of our students does) should not have to pay for extra training!
For business use you are looking at a CPL. There is a reason that 200 hours total time and an extra 25 hours flight training plus an awful lot of groundschool are required for the holding a CPL. That reason is exactly what you are talking about
: you can do a whole lot more with it, and are expected to be able to cope much better with a broader range of situations.
It's no secret that the airline industry is not content with the quality of new CPLs. The ICAO has proposed the new co-pilot license. these are signs the the current system is flawed. What suprises me is that a new CPL can be allowed to do 6 TOs and landing in a multi-million £ Jet after 'only' 40hrs in the sim, yet they cannot be allowed to fly PA34s with passengers IFR.
It may be no secret to you, but it seems to be a secret to those of us that actually work in commercial flight training. The proposed co-pilot's licence would actually be of a lesser standard than the current CPL/IR, and would not allow all the privileges.
If you really knew enough about flying to go waving these random criticisms of the flight training system in a forum full of people in the business then you would realise how much harder single-pilot instrument flying is than multi-crew. Notice that many commercial operators have AOCs which in fact restrict them to pilots with more than 1000 hours for single-pilot ops.