The 3-phase High Amperage Charger in all facelift Model S and all Model X ordered before July 1, 2017, was software limited to 11 kW although the hardware is capable of doing 16.5 kW, unless one chose the option to pay a fierce premium for those 5.5 kW more in AC charging rate, which is still offered by Tesla as an upgrade for 2100 (!) EUR. The unlocked High Amperage Charger became the default on all orders after that date without surcharge.
Obviously it is just a very bad idea to unnecessarily limit the charging rate, especially for the ones waiting in line behind you at a destination charger. With more and more vehicles on the road (and the flood of Model 3 coming to Europe now) a difference of 50% in charging rate (11 vs 16.5 kW) makes a significant difference for the occupancy of destination chargers.
The optional High Amperage Charger upgrade (which indeed was just software limited in all vehicles that can utilize 3-phase power) was simply too pricey from the beginning, and never showed up in the customer account as a possible upgrade, so it has to be assumed that a very high percentage of (facelift) Model S and Model X from the pre-July 2017 era is affected by that issue, most likely with the majority of owners not even aware that their AC charger could do better without any hardware change.
Obviously it is just a very bad idea to unnecessarily limit the charging rate, especially for the ones waiting in line behind you at a destination charger. With more and more vehicles on the road (and the flood of Model 3 coming to Europe now) a difference of 50% in charging rate (11 vs 16.5 kW) makes a significant difference for the occupancy of destination chargers.
The optional High Amperage Charger upgrade (which indeed was just software limited in all vehicles that can utilize 3-phase power) was simply too pricey from the beginning, and never showed up in the customer account as a possible upgrade, so it has to be assumed that a very high percentage of (facelift) Model S and Model X from the pre-July 2017 era is affected by that issue, most likely with the majority of owners not even aware that their AC charger could do better without any hardware change.