600mm isn't the largest in the UK nor in the EU or Turkey. It's the "standard" size and most 5kg washing machines are 600mm, but there are also 700mm, 800mm and I believe 900mm units which can take upto 12kgs of washing at a time. The larger machines also tend to be higher and won't be suitable for slotting under a worktop.
The same applies to fridges, fridge/freezers and cookers etc.
In all cases you should check the dimensions in the manufacturer's catalogue or on their website.
