Yes there are multiple systems in testing or production which do battery KERS e.g. Fortescue‘s roadrunner mine truck. There are also trains which do energy reco

Yes there are multiple systems in testing or production which do battery KERS e.g. Fortescue‘s roadrunner mine truck. There are also trains which do energy recovery but shove it onto the network e.g. Sweden’s Malmbanan. As you note direct gravity devices are centuries old: water balances, gravity balances, paired boat lifts (like the Falkirk wheel), …