In every industry, there are employees whose influence on the company success is outsized, and who are hard to hire or train. In software industry, they are experienced engineers and product managers. In a fashionable restaurant, they are experienced cooks. In an airforce, they are experienced pilots and repairmen. Etc.
When these people are happy with their work, they achieve great results. When they are unhappy, they look for ways to conveniently jump ship, because they have a number of opportunities elsewhere waiting for them to become available. They are in short supply. Every boss has an incentive to keep these people content and loyal.
OTOH every industry has positions for which supply is plentiful, compared to demand. Aspiring game developers without experience, dish washers, burger flippers, etc, can be readily hired, paid little, and easily fired, too. There is no incentive for their bosses to walk an extra mile to keep them happ, especially when pressing them a bit more yields an extra bit of performance, so they mostly aren't happy about their jobs.