Toyota Rav4 'trailer sway control'

Looks like it's a variation on traction control/Electronic stability control https://www.toyotaonthetrail.ca/2016/06/09/how-does-trailer-sway-control-work/ 

IMHO they'd work together rather than fight each other

Mollysmum is correct....our Subaru with trailer stability operates on the car only in response to the extra load and mass of the van on the rear end. In reality the self levelling and the subsequent firming up of the rear suspension as a result of it takes most of the instability due to pitching etc out of the equation anyway.

Tj

Trailer sway control-controls the vehicle not the van

ATC-controls the van not the vehicle. best of both worlds.

It does enable the car to oppose the forces acting on the car due to a swaying caravan, though.