While my sample size is small, I don't necessarily disagree with you, but many coders are hired like this as consultants and independent contractors. They often work through contract employment agencies, who receive a portion of whatever their hourly rate is. They're temporary, and once their contract or project is up, they're onto something else. It can be a living, but there is a degree of uncertainty in this employment lifestyle. It's certainly not for everyone.
“They’re temporary”
As are the a number of employees these days. It is now a “gig economy”.
I have seen staffing at 100% contractors, and most Fortune 500 are easily 30%+ staff augmentations. I have rarely seen employees with more than 4 years company time. Turnover is so great that they might as well be temporary workers. Heck, I’ve seen contractors at a company longer than the company staff.
The days of hiring, training, and retaining technical employees is over, and has been for 15+ years.