Why do the Nespresso machines operate at 19 bars of pressure, whereas all the others are at 15 bars?

The capsules used in Nespresso machines require a greater pressure in order to release their contents.

By the same token that the 400 hp Land Barge can neither develop the advertised 400 hp, nor could it use more than a fraction of it in any sane driving situation, 19 bar (180psi) is far beyond the SCA standard 9 bar required to brew espresso coffee drinks.

You wouldn't like a shot brewed at 15 or 19 bar. The grind and packing of the coffee would have to be wrong in the first place.

'tain't so McGee- Advertising Palaver IMO