Long Inbuilt Network Delays

This is a networking question at the top tier level.

Why does ATT, and others, deliberately insert a long delay (500 ms) in all packet traffic at major gateways. This is plain obvious for traffic across major links (Pacific, or to Asia, etc). I can ping plott over a few hours, and it's easy to see this is deliberately inserted delays, and manipulated as they choose.

Is this the major players trying to channel traffic through other major connnections? Or them giving priority (or non priority) to various major ISP's as they choose? Or them pretending they have run out of band width?

Yes I know at this time the Taiwan problem exists, but this happens all the time year round, and fluctuates at very predictable amounts at various times of day.