The VZ is sort of an unfair example, as the comparatively low price was due to the use of mostly surplus parts. Every single part other than the Receivers themselves was surplus, and (as it turned out) many of the Receivers were actually "repurposed" VZ-58 military Receivers with some judicious welding and grinding done to them! Anyhow, an unfair example because the guns were largely comprised of ultra low-cost surplus parts.
As for the AR15, it is "America's Rifle" based largely on its continuous use in military M16 guise for the past 60+ years, but also because the AR is highly reliable, accurate, durable, ergonomic, lightweight, adjustable, ambidextrous, light-recoiling, and infinitely adaptable due to its modularity. Because of its incredible popularity in the USA, there are estimated to be well over 500 major AR-related manufacturers pumping out parts on a continuous basis. There are bound to be low-cost examples on one end of the manufacturing spectrum, with costs kept down by sheer volume and economies of large-scale production.
Any other semi-automatic design, whether derived from a national military requirement or a clean design sheet, will see miniscule worldwide civilian sales in direct comparison to the AR15. Even CZ, who claim to have products in use in over 90 nations, will never produce enough semi-automatic "Bren 2 MS" rifles, carbines and "pistols" to put a dent in AR sales. It just won't happen. So the cost-per-unit of lower-volume production is inevitably going to be higher. Then factor in the effects of today's 5%+ rate of inflation, and it only stands to reason that "small-batch" semi-automatic firearms today are going to cost far more than rifles made from surplus parts or manufactured in immense volumes, especially when you compare prices today with prices years ago. It is just common sense.
Notwithstanding the above, it is entirely understandable to commiserate the meteoric rise of commodity prices when you compare the cost of things today with their prices in yesteryear. That applies to everything, from semi-automatic, military-style firearme to the cost of groceries or fuel. Inflation sucks. Thank Truedope and his fanatical eco-followers for our current runaway rate of inflation. I firmly believe that things are going to get much worse before they can be turned around for the better in this country. Thank God I live in Alberta...