Is there some preventative maintenance that can help alleviate this common issue?
Other than keeping your furnace filter clean (check it once a month) and washing out the fuzz stuck inside the condenser with a garden hose every spring, unless you notice a ridiculous amount of vibration or unless you know you're low on refrigerant, then there's no reason to call a guy out and nothing more you can really do.
That "Leak Stop" stuff is a stop-gap (it's worth a shot though). If your system is low due to a leak then it's on its way out. It's up to you to spend ~$100 a year to probably continually leak Freon, or drop several thousand up front to not to.
Anecdotally, no one 'goes on' about their working AC unit. The failure rate on condensers by year five is less than 10%.
Why are HVAC systems so susceptible to failure?
It's probably the most complicated machine in your home, subjects itself to vibrations and the weather, runs at pressures upwards of 400 psi, passing refrigerant through flimsy copper or aluminum tubes that have about a thousand solder joints.
Most manufacturers have different grades of equipment, but most of the improvements they offer are for comfort or a slight increase in efficiency - but every split system ever made still has to contend with the above.
Is this the way the "industry" or "man" keeps HVAC service companies in business?
Yes, but not in the way you're thinking. The 'industry' could care less about service companies. What they care about are the installers they sell equipment to, and you'd better believe that they build them as cheaply as possible. And that's why the term builder grade A/C unit exists. It just needs to work well and long enough to sell the place. Like all things (they fall apart), it comes down to economics.
I'll take a wild guess that your system doesn't have a nameplate on it that says Carrier or Train (or any of their subsidiaries) - you get what you pay for... I'm looking at you, Goodman :\
Most Reliable Central Air Conditioning Systems – Consumer Reports
Still, two-thirds of the owners of American Standard systems are likely to be completely satisfied with the performance of their A/C system by year five. Owners of Goodman systems are predicted to be the least satisfied followed by Rheem.
By the fifth year of ownership, the evaporator coil is the part most likely to break, with Rudd, Rheem and York being the brands most susceptible to this problem. However, this problem is only likely to affect less than 10 percent of all units by year five.
Regardless of brand, when a repair is needed, most of our readers told us they pay out of pocket. Rheem owners paid a median repair cost of $252. Lennox wasn’t too far behind at $236. Somewhat less expensive to repair out of pocket was Carrier, at $200, followed by Goodman at $204 and Trane at $219. We didn’t have enough repair cost data on systems from Amana, American Standard, York, Bryant, and Ruud to report on them.
Therefore, fixing the problem will require a professional.
Well, not literally. You just need the tools, the knowledge, and a license to buy refrigerant. Free free to become an AC tech at any point... No? Well, that's why it costs so much money ;)