Yes, when 50 years old applies as a senior engineer, 25 years old senior engineers get uncomfortable. You might not notice it in any public conversation, but there is still a resistance: * will they be on-call? * can they work long hours? * how do I delegate to them? * are they going to resist new tech?
Reply to below:
Of course. But if you plan ahead properly, it will be extremely rare. To the point where it isn’t economical to have people on call. Because the downtime was caused by a meteor or maybe AWS.
If it is truly mission critical, have a night shift.