Morning 602,
A couple of points here.
Manufacturers cannot make retrospective changes to the vehicle specification due to homologation rules. Once homologated to a given market, that's it - no change permitted.
VIN plates. All vehicles built since 1979 must have the standard 17 digit VIN plate. It is a global standard which details the manufacturing country, model type, model year and so on. Japan is no different on this. If a vehicle has no VIN plate, it has no identity. No identity means a whole big can of worms.
The VIN plate itself will vary depending on the destination market, but does not have to state the towing capacity in most countries unless it is a specified requirement. What is usually mandatory on any VIN plate is the GVM (Gross Vehicle Mass) or individual axle weights. Information such as GTW (Gross Train Weight), Max Towing Capacity and draw bar max nose weight are not usually found cluttering up VIN plates. The reason for this is that so few passenger vehicles have a towing requirement. Tow packs are an option, not standard fit, so information is placed on the tow bar itself and in the owner's literature.
The UK rules on trailers for passenger vehicles is quite clear. The max you are allowed to tow as an unbraked trailer is 750kg. That said, that is the legal position. The position of individual manufacturers may differ and apply lower limits (or not permit towing at all). The issue now is that most modern vehicles have enhanced driver aids such as varying forms of stability controls. If you add a trailer, many vehicles now need to know a trailer is fitted to compensate for these systems. As this requires extensive and costly testing, you will find now that many vehicles don't have a tow bar option.
The moral of the story is to do the research and check the specifications of a given vehicle very carefully.