Consider the lowly econobox with a biggish four-cylinder motor. Suppose it's geared to do about 2500 rpm at about 60 miles per hour. With proper maintenance, that engine should easily last 15-20 years in service and cover 240,000 miles. If we take 60 mph as an average, that's ~300 million cycles of its valve springs, at a typical rate of ~21 cycles per second. Lots of time will be slower, lots will also be faster. Typical temperature will be in the realm of 250 F. At the end of that time, the valve springs will still be serviceable. If we pull the engine apart to restore valve seats and piston ring/cylinder wall surfaces, we'll replace the valve springs so the new ones can go another 300 million cycles. Furthermore, I can usually buy those springs for about what a typical gun spring costs, when the gun spring contains far less material and is generally manufactured to much more variable standards.
In contrast, we're told to change many gun springs at 3000-5000 cycles. H&K USPs are dramatic outliers with a recommendation of the main recoil spring at 25k cycles, if I remember correctly.
(This semi-rant was inspired by contemplating the Manurhin MR73, considered by many to be at least among the finest revolvers ever made, where the most credible reports of serious operating problems seem frequently to be tied to poorly performing springs.)
From a 100,000 times difference in service life, a reasonable person might conclude that the vast majority of gun springs are either poorly designed applications, or the parts are made from crummy materials using crummy processes.
Any spring engineers in the house?