Can't I just buy a Zojirushi or other rice cooker from USA and import it?

No. USA units are not compatible with UK and European power supply (they are 110V and 60Hz) and you would need to purchase a bulky and expensive transformer to convert the voltage so you could use it. Transformers for stepping up voltage take up a lot of electricity when converting voltage, are bulky and don't convert the cyclical electricity frequency of an appliance (ie they don't convert from 60Hz to 50Hz). We have had several customers who have tried to use US rice cookers with a voltage converter and they do not work or broke within 6 months.