This has been asked and answered so many times on the forum, and is also clearly explained in the manual where refueling is discussed:
IMPORTANT
There’s a minimum height the Fuel Truck with an extending platform can use, which is about 3.00 meters from ground for the Tanker and 3.40 for the Hydrant. If the airplane refuel point is lower than this value, a different vehicle will be called, one without a raising platform or a crew with a cable animation
So no, the tanker in your screenshot is not wrong, it's exactly what you are supposed to get on a 737. And as explained on the Sticky threat about future updates, a new vehicle IS coming:
https://www.fsdreamteam.com/forum/index.php/topic,27778.0.htmlNew Fueling vehicles for airplanes with lower wings like the 737 or the MD80
There will be a completely new animation, with the refueling crew using the Fuel cable roller to connect to the airplane refueling point, not using a raised platform, but either a small ladder, or just by standing if the wing is low enough. Both Fuel Hydrants and Fuel Tankers will be updated with this new animation.