Netflix pays exceptionally well and is very selective, and I understand they are quicker to fire underperformers than most. So it is fairly prestigious and ranks at the top in compensation.

I'm guessing it's from the financial perspective, not a technical one. Netflix is a reasonably stable, well-known brand worth over $100bn and that has 100m+ subscribers.

From a salary perspective, I'd suspect they have to be competitive with the other companies for tech talent, so it's reasonable to include them here.

Netflix and Apple are both weird additions. A lot of people skip Apple (FANG), but these days a lot of people just mean "big tech company" with it.

The acronym without Netflix is less than desirable

They are know for high compensation

Because they are known to pay more in salary than the average tech company.