Trailer dock restraint styles?

This is more of a warehousing/retail distribution question, but this looks like the best place to put it. I work maintenance for a large company, and at the campus I work at one of the buildings contains a large scale print shop, which processes something like 8 million feet of paper per day, and the result is a whole lotta trucks. On the docks there are two styles of restraint, the hook kind (http://ift.tt/1g5Rm7B) and the wheel lock kind (http://ift.tt/1g5RkwJ). Now from a maintenance standpoint, the wheel lock kind is horrid. A quarterly PM takes two hours because you have to take all the covers off the length, lube everything, put it back together, then go find a semi and get the driver to pull in there to make sure it is working smoothly (this is required by the property owners, not the manufacturer). Annual is even worse because you have to torque all the bolts on it, and there are a lot. From a functionality standpoint, they're horrid. I would say that once a month a driver misses the thing entirely, backs OVER the lock, and gets his truck stuck; at which point the dock workers call us and we say "What do you want us to do? Call a tow truck." Every once in a while someone tries to back a pickup truck into the thing too, which bangs up the rear wheel well pretty good.



So my question to you fine gentlemen (and gentle-ladies if there happen to be any about) is, does the wheel lock style have any advantage over the hook, and if so what are they?