A lot of really practical ideas are going by the wayside I feel, because the driving public has dummied down in proper usage.
A manually operated differential can be extremely hazardous on the front in fwd (that’s why you won’t see them there), and potentially bad on the rear in rwd if left on and driven by an inexperienced driver. If you think an open differential fish tails, it is nothing compared to a locked differential when both rear wheels loose traction on ice. An open differential has one tracking wheel remaining even though it has less ultimate forward traction.
Because of the added safety of a computer controlled system, I feel on road driving is much safer with these nearly as effective systems though at low speed off road only conditions, manual lockers are preferred by most. Operating these manual systems can also severely reduce the life of the rear differential if use improperly. All things considered, let the big boys and genuine off roaders on specialized vehicles use them; the rest of us should be content with traction control systems.
My 4Runner has an electronic off road version that allows down hill assist in off road conditions that are impractical with most manual lockers. This is good for we off road wannabee weaners and safer if we “forget” where we are and what we are driving.