I saw that several Chinese factories offering their clones of the current Yamaha Gear generation (I think that those are 50cc only), with four-stroke Honda GY-6 clones from 50 to 125 and 150 cc.
Because of that, I believe that this delivery scooter, inspired by the older generations of the same Yamaha Gear, for the same price, can easily get more powerful engines.
And yes, I can agree with you - 50 cc four-stroker on something that is not lightweight moped, in manic city traffic, is real punishment.