Getty’s strategy at the time appeared to be to meet any infringement accusations with a massive legal response. Any individual photographer could generally not afford to respond.
My impression was that they were not super concerned about infringing on other’s work. But they will sue the pants off anyone who they perceived to be violating their copyrights.
But in recent years there are legal firms dedicated to pursuing deep pocket infringement cases on contingency. This has changed the legal calculus for large companies who were not careful with copyright.