Rigid metal pipes are invariably used in the UK for gas supply within buildings. Only short lengths of flexible tubing are allowed for final connection to gas cookers or other appliances that need to be moved.
The odd accident no doubt occurs but it does not seem to be a significant risk.
The only pipe I have seen here like that is called Tracpipe. Its intended as an alternative to copper piping. Not for final connection to appliances. I've used it a few times with no issues and never heard of anything like this happening with it. I'd be surprised if ordinary copper pipe would pass the lightning test they subjected the CSST pipe to.
The black iron (or MI as we call it here) might be able to survive a lightning strike but it is very rare to see that used in a domestic installation. The time and cost in fitting MI is much higher than copper and CSST.
28 years as a firefighter and i never saw that as a problem. I guess that as any pipework that is installed badly can be a risk: things like flexible attract people who are not really qualified or experienced, as it can seem an easy option. So maybe you're more likely to see flexible pipe in a poorly designed installation, rather than flexible pipe being poor? Then it gets sensationalised, like the Bermuda triangle or the Loch ness monster.
