If you look on fordparts.com, the 2017 2.0l Escape with factory trailer tow package lists larger (and much more expensive) radiator and more powerful and higher wattage cooling fans (50a circuit vs 40a). In addition to the 2000lb/3500lb weight difference the trailer frontal area is 20 sqft. vs 30 with tow.
The sales person (who I've known for years) that I bought my Escape from primarily deals in Ford truck sales (F150-550) said he wouldn't be surprised if the programming of certain ECM functions regarding shift strategy, engine cooling, engine control parameters were also tweaked by the factory when the tow pkg. was optioned.
I would have liked the package, but there was not one Escape in stock in a 100 miles with it. At most, I might pull a little utility trailer around town, so this wasn't a big concern for me.
IMHO, a regular Escape could probably tow 3500lbs/30 sqft frontal area in mild climates, but mountain driving and/or very hot weather may tax the cooling system.
2017 Ford Escape SE 200A
2.0 AWD, Ingot Silver
Cold Weather Package