I noticed the same thing when I test drove mine before purchasing it. when I questioned the dealer about it, I was told the same as you were. (I bought it anyway) When they delivered it, I tweaked the top half of the door frames. (Basically bent them in to seal against the roof.) There is also foam rubber like material between the windshield and above it where it meets the roof panel. Dealer put them in crappy, so I corrected that. And last, there are 2 small black plastic plugs in the cowl between the rear of the hood and the windshield. They are not sealed at all. You can either replace them with the same type rubber plug, or remove them and reinstall with a bit of RTV sealant. Granted, the cabs are not 100% "Water/leak-Proof" but these few things will limit the amount of water getting in to an acceptable level. Cab isn't of the highest quality to start with. While you are taking care of small issues, upgrade the cheap, thin retainer straps with snaps that limit the door swing. Light wind caught my door and snapped it right off. Upgraded to military style 1in nylon tie-down straps and loop anchors. Both from Amazon.
https://www.amazon.com/gp/product/B001O0DE0S/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1