Bravopilot The special tourneys are limited fields but not capped.
In a way, they are. Very specific qualifications must be met...no 'qualifying' days to get in. TW does not qualify for any of them, even if he'd won 1000 tournaments. But neither do a couple others that are being given exemptions every time. TW's exemption though allows him to enter at will, every tournament in the rotation of them, without being asked/chosen.
Bravopilot I don't know if The Open has field limit.
Here again, there are certain qualifications in order to enter, except they do have 'qualifying' days in order to gain entry when not otherwise eligible.
Regular PGA tourneys are much the same; not 'just anyone' that has a PGA card can get in most tournaments. Unless given an exemption by sponsors.