Your basing your comments about chinese PCBs on what? Actual fact or just the standard china is rubbish mindset?
Protos often use a cheaper(?), weaker, glossy soldermask. This is at least true of PCB4U, PCBCart, ALLPCB and ITEAD in my experience, and most likely the other budget services.
My experience with PCBCart full custom has been they use a stronger soldermask. Most western fabs use a glossy or matte formula with good to excellent strength (e.g., Advanced Circuits, Eagle Electronics, etc.).
It may just be coincidence that these are all Chinese fabs using the formula in question. More likely, it's simply "you get what you pay for".
Tim