Technical Fuel block on firewall; hard lines to carbs question

Where I work we have some rather large air compressors that have been running at least fifteen years at about 16 hours a day.
There are gauges on each of them plumbed with plain old 1/4" copper tubing (45 degree flare fittings), and they vibrate noticeably. They are working just fine.

Typical steel tubing does work harden less than copper tubing, but copper doesn't in my experience merit the criticism many people give it.

I wonder if some of its bad reputation came from the use of compression fittings on it?

However, I'm not endorsing the above solid copper (or steel) line from fuel pump to firewall. The engine and firewall move a fair bit in relation to each other. But I'm not going to complain about it either.