First, this is not a means where I would care about glitch free operation, more about the equipment surviving.

Agreed, if directly hit by a lightning.

But: If a thunderstorm is gathering, grounded metallic framework is exposed to invisible discharges of electrostatic charge in the air, common mode noise is fabricated.

Isolated wires and cables spanned some meters over ground can carry some hundreds of volts, even if they are NOT hit by direct lightning. If this overvoltage is shunted to ground via protection circuit, also common mode noise is fabricated.

Second, I have yet to see an insustrial plant with a ground mesh.

But you did see plants, where metallic framework is connected to earth potential at several points? Ground mesh or grid does not mean 'ground plane'. It describes the methode of having connected metallic framework at as many points to earth potential as possible. The more the better.

Here in Germany, where industrial environment must obey CE standards, a whole industry is growing, helping to transform plant into high frequency suited environment. One task is to make ground mesh tighter and tighter, by connecting 'everything to everything'.

Kai