Please consider the barometric formula which takes into account the temperature and molar weight of the various elements involved.
It's a (pseudo)exponential function.
The elements on earth are especially light because they are protected from solar wind by the magnetosphere. On other planets and moons the gas is much colder and often composed of heavier elements.
When you add the 3-4 times heavier molar mass of the CO2 and SO2 on Venus and the temperatures, the exponential barometric formula results in much higher surface pressure.
