It's not about pay, it's about delivery windows. The driver gets paid nothing relative to the cost of late delivery. Companies also aren't going to hire the trucker that quotes an extra day because of charging.
And 30 mins of charging every 8 hours is unlikely to significantly change the delivery time anyway.
Companies are in the business of making money, if a private contractor is cheaper (and faster) than their in-house logistics who do you think is going to be axed?