You're vastly underestimating what sort of effects "peak season" has. UPS hires 95,000 temporary employees each year; FedEx hires 50,000. Amazon hires 120,000. Retail scales up similarly, but I'm less familiar with the industry.
"A few thousand" is how much single distribution centers scale up employment.
So Amazon currently hires 120,000 people at $12/hr for 10 weeks for a total cost of somewhere near $576M. This counts as COGS and is included in their gross margin. If we just multiply that figure by (52 / 10) and subtract out the $576M, we can see that it would decrease their annual Gross Margin by $2.5B. Add on an additional 30% of the combined $3B in salary expense since I doubt the temp workers get benefits, and you'd be looking at a total of ~$3.4 billion.
So in 2016, this would've changed their gross income from $47.7 (35% GM) billion to $44.3 billion (32.5% GM).
https://a16z.com/2014/09/05/why-amazon-has-no-profits-and-wh...
For that matter, not any different from a typical person. Expenses that you would be better off not incurring are, by definition, frivolous. In the case of Amazon, frivolous spending at any level changes the price at which they can achieve a fair margin and reduces customer satisfaction.
Their constant argument every time is "we have no viruses, why do we spend money on this" and I have to tell them every single time "that you're paying for it is WHY we don't have viruses." They have no idea what viruses are, what malware is, what ransomware is and despite being hired to maintain infrastructure, I must continuously explain my decisions to people who do not maintain infrastructure and wouldn't know how with a gun to their head. This, to me, is stupid.
Nobody hires someone outside their domain of expertise and then leaves them to do whatever. Your constantly justifying your recommendations is, like it or not, a critical part of your job.
I wonder if you would still act so idealistically if you held stock in the company..
Side note; I do hold stock in the company, and because I'm not an asshole, I do think they should rely less on temp labor and they should improve working conditions for their existing warehouse workers. Even if it reduces my capital gains by some fraction of a percent.