Cheap in that they simply do not care about the situation in which their device is going to be used? Yes.
Cheap in that they simply don't know any better? Perhaps.
The savings over doing a proper single phase, intended to be hard wired to the premises, inverter vs what they have done is IMO minimal but in a country where they will use an elcheapo knock off of a reputable microcontroller*, that costs 10 cents, as opposed to the knock off that costs 9.5 cents, it's not surprising.
*actual real world example, dig into the FTDI USB serial port debacle for more