In defense, you have lower pay, but also better job security and less age discrimination. You'll never have to brush up on how to reverse a linked list. It's also a very 9 to 5 job, there's no oncall for systems that are largely offline, and rarely is there Agile. You put in your hours and clock out for the day.
Generally defense contracts pay very well, and pay hourly. Benefits are usually generous. Work is generally 40 hours a week, but if it is more for some reason, you get paid for each extra hour. If this is not your deal, you're working for the wrong company.
Age discrimination is generally much less, but can be a problem on certain contracts. Sometimes the government thinks they'll save a bundle by getting less experienced people to do the work. They usually repent of that the next time a contract comes out. The experienced / good people can always find another contract to go to.
I've seen all manner of processes from very well done agile, to poorly done agile, to waterfall, to no process at all.
On call depends on the contract, but is not typical.
Less than 0.1% of software jobs are FANG. This is not a sensible comparison.
Picking something more normal, Tesla pays software developers just $78k to $147k. Raytheon can beat that. This is without even trying to adjust for hours (a 9-to-5 place, or Elon Musk cracking the whip) or the fact that Raytheon locations typically have a far lower cost of living. Just on raw numbers, totally unadjusted, Raytheon wins.
More "normal"? Are we looking at whether it pays "normal" or pays "very well"? Don't get me wrong, in the world of all jobs, a defense job is really good, stable, and comfortable. Good to raise family on and have balance. In the world of tech, it's barely mediocre and the lack of stock options, bonus, or any perks to speak of (often not even free coffee) make them struggle to attract the best CS talent. Google pays very well in this field.
There is "very well" and then there is "statistical anomaly".
Google pays almost nobody. The whole firm, called Alphabet, has just 98,771 full-time employees. Most of those are not really "in the world of tech" though, with many devoted to stuff like marketing and human resources. It looks like about 40,000 are engineering talent, but not all of that will be software.
There are over 40 million software developers. At most, about 1 in 1000 work at Google. Again this assumes that all the technical staff at Alphabet is software developers working for Google, but that assumption is clearly wrong. There are hardware people working on cars and phones and more.
That 0.1% is practically nothing. Approximately nobody works for Google. It is just crazy to use Google as a standard for tech pay.
It's like asking why an athlete would be a gym teacher when the NFL pays so much better. It's like asking why a person would give kids private music lessons when you can make so much more money singing like Madonna. It's like asking why a person would be a mayor instead of being the US president.
Furthermore...
You are incorrect about the benefits being offered at defense contractors. Some do have free food, bonuses, decent pay, and even stock options. I've gotten all those things at defense contractors. Another advantage is a 40-hour work week. Another advantage of many defense contractors (not all) is that your coworkers are trustworthy American citizens who don't behave erratically; they have all passed a background check.
The government makes these companies keep track of their hours for audit purposes. So while some rare people may work overtime and not log their hours, there is really no culture of working long hours there.
To elaborate on why the job security is so good, it's because of the clearance system. During the internship, my manager said that if I wanted to come back next summer I would have to get top-secret (TS) clearance. Almost everyone working there has at least secret (S) or TS clearance. Getting clearance takes ~1 year WITH an employer backing you, and it may take years (a.k.a impossible) without one. So once you're in the system with clearance, you can bounce around the def-sec world forever.
