The highest bar pressure is not necessarily the best or most efficient machine for cleaning. At Duplex, we have a saying which is "you can't beat physics". On standard 220/240 volt machines (or 110v) you are limited by the power supply (3 -3.6 kw whether a 13amp or 15 amp plug is fitted) and also the boiler volume.
The higher the exit pressure the less volume of steam is delivered to the cleaning surface. Think of the analogy of putting your finger over the end of a hosepipe; the volume is the same. Steam Cleaners are effective as they use the temperature combined with some agitation.Glossy advertisements showing a plume of steam might look impressive but in practice achieve nothing.
All the temperature, hence cleaning efficiency, is near the tip of the nozzle and outside that area the reduction in temperature is dramatic. In fact in some cases, such as Healthcare applications a higher pressure might spread dirt particles.