limeyphil:
simple. ask the boss for more money. and if you are worth it, he’ll give you a rise.
Trouble is, if the boss isn’t worth it he won’t!
I don’t believe drivers will ever have any real market forces control over their pay & conditions until haulier insurance becomes so expensive, that everyone is forced to be self-employed on top dollar because so many of us won’t hear of doing self-employed in this country that penalises it!
Eg.
Drivers needed for cover
Local SE want to charge £20 per hour.
Agency offers dross for £9.00 per hour, so some get booked.
INSURER increases premiums by 1000’s because of the higher perceived risk of accidents with dross drivers
FIrm doesn’t care, and plugs on. Accidents happen, insurances goes up and up until premiums are unaffordable. Firm begins to run bent, starts employing SE cash in hand ■■■■■■ to get around paying top-dollar, but they have no insurance either.
More accidents occur, people die, people start going to jail. No one was saved, not even the children. 
or
Drivers needed for cover
Local SE want to charge £20 per hour.
Agency offers decent drivers for £15 per hour, firm reluctantly accepts.
Insurance premiums stay low, whilst other hauliers in the (a) disappear. Firm is finding it hard to make much money with such high overheads. 
or
Drivers needed for cover,
Firm circumvents agencies (too expensive, or only dross on books) advertises full time jobs with strict entry requirements (eg. 10 years experience, 0 points, must have driven a variety of different types of runs)
Jobs advertised at today’s better rates, but still way below what it could cost if they hung on. Eg. £600pw 40 hours.
Firm stays in business during sharp economic upturn, driver knew what nasty job market he was leaving behind for such plum T&Cs, so commits to stay a long time, customers & insurers happy because trouble is almost non-existant. Firm prospers & expands over the coming years. 
At the moment, insurers don’t give a toss, because they’re on a bailout promise akin to the banks. Perhaps one day soon they’ll be credit crunch/insurance collapse part II but without the anticipated bailout this time, and the game for the economy really will be changed at the ground floor in the way I’ve described in option 3. 