And because, until relatively recently, only one or two units of the Czech Army used CZ pistols. The Czech National Police and other police units in the country have used the PCR and now the P-01 for some time. The CZ-75 was designed for EXPORT, and the West's embargo of Communist products kept exports limited. (The Soviet Bloc didn't use the 9x19 round and it was very unlikely that a CZ-75 would have ever been used by a Communist military unit -- except perhaps special operations units.)
Police units don't use their handguns all that much, and as noted above, military units don't either.
Some years ago, before apartheid ended, South Africa used a number of CZs; they hit the "surplus" market in the U.S. a while back. The Israeli military used a bunch of them, along with a bunch of Tanfoglio weapons -- and then they started making their own, based on the Tanfoglio design (which is similar to, but not the same as the CZ.)
All that said, there are enough CZs out and around that if there was a problem with longevity, we'd have heard about it. They seem to be just as durable as any other service pistol. I've put maybe 15K rounds through a CZ-85 Combat, and many thousands of rounds through a variety of other CZs, without problems.
Most of us -- the typical shooter who isn't into intense competition -- would be hard-pressed to put 30,000 rounds through a single gun in 10 or 15 years; many of us have other guns we like to shoot, too -- and ammo isn't cheap. <grin>
