I'm not sure what you're comparing but it sounds like you're comparing experienced vs. inexperienced and not necessarily older vs. younger. I'm 57 and I don't think I am that much more expensive than younger experienced backend engineers and SREs. We're all as a group a lot more expensive than people who are just starting out but that's hardly surprising. Between those of us who would be considered senior in terms of experience I might be $10k or $20k more expensive just due to salary history and growth over time but I doubt that amount is a deal breaker for the average tech company.