Being a bit of a jaundiced old dinosaur, I lament the disappearance of some of the valuable checks and balances we had in days of yore, especially in the freight game.
Things such as -
(a) the flightcrew checked the can tags prior to loading as the trucks came up to the aircraft - weight and order - for subsequent checking against the load sheet data
(b) the shed ran the calculations using a manual trimsheet. The flightcrew then ran a check on the trimsheet against the can load data previously obtained (to check weight and order) with one crew member running a CG check using a circular, prayer-wheel style of trimsheet. This could be done as quickly as the captain read out the trimsheet weight entries.
(c) as the flightcrew generally couldn't get access to double check the locks, the loaders were rigorously trained to be highly aware of lock integrity, especially in the case of empty bays.
Didn't mean that there were never any mistakes made, but the risk was kept pretty low. As I recall, the only significant embarrassment was on a wet night departure - water had got into the innards through the freight door and there was a major electrical failure during rotation. Fortunately, the crew kept their cool and all was well ... if a little sweaty.
From a flight standards and training point of view, perhaps an early rotation or other indication of significant misloading (tiller responses ?) should be sufficient reason to reject the takeoff/taxi and return to the shed for a check on the load.
I can recall one case where we had an interference problem with the weighbridge and all the weights were wrong. The crew rejected the load (can't recall now whether on taxi or takeoff) and took the aircraft back to the shed, at which stage the weighbridge problem was detected.
One fleet had an on-board oleo weight and CG check system. Always gave wrong numbers but they were consistently and predictably wrong so the check on taxi was useful. As I recall, there was at least one occasion during my time on that fleet where a significant misload was picked up on the taxi and confirmed when the aircraft returned to the shed for a load recheck.