As for the flight needing to be cost shared between the 'persons' and not the 'companies', that doesn't matter. The companies are either hiring the aircraft, or own the aircraft. Either way, the law looks upon it the same.
Fairy nuff. Just seems to stretch the cost-sharing law a bit. What would be the legal cost-division requirements if there were 2 people from Company A, and one each from B and C? Same thing as for individuals, A must pay for 50% of the hire costs, and B/C 25% each?
What if I have a PPL, 3 guys I've never met before from Company X want to fly to ABC for work, and I agree to fly them there and absorb 25% of the hire costs myself? Same thing - essentially a charter operation, but legally can be flown as a private op, as it's for transport only (no goods carried), the costs are shared equally and I receive no money or benefit from the flight?
If, however, a salesman takes samples or other such things with him or IIRC a tradesman takes tools with him (not sure about the tools one but definately the samples one) then the flight is for carrying on business and so Aerial work.
Makes sense and ties in with the highlighted bit in tmpffisch's post (#4).