"I replaced the bulbs on both sides to keep balanced lighting."
Excellent move. The operating hour life of automotive headlight bulbs is extremely consistent, and if one side burns out the other isn’t far behind.
Your are correct about the inverse relationship between the cost and the lifespan. “Standard” quartz-halogen headlight bulbs have an operating life of 1000 hours. As the price goes up, the output goes up, but this is accomplished by burning the filament hotter, and this shortens the operating life of the bulbs.
The “standard” bulbs for my car cost about $12 a pair with a life of 1000 hours. The ones I use, “Superstar Ultra” bulbs, cost $50 a pair, and the lifespan is rated at 250 operating hours. But they put out a lot more light. Sylvania sells five different levels of the “Superstar” bulbs, each “upgrade” putting out more light but at the expense of lifespan and added cost.
It’s entirely possible that the guy at AutoZone really didn’t know this. Most people don’t, and my experience with AZ counter people suggests that he may have actually been surprised… I’ve been very unimpressed with the level of knowledge of many of these people. If fairness to them, the qualifications for the job aren’t high and that’s reflected in the modest pay rate.
Oh, and I don’t think it’s gender bias. It’s simply lack of knowledge. I no longer stop at AZ stores, because of unsatisfactory experiences.