Yeah basically. For IOW "sold out" generally means "sold out at whatever we configured it for". The exact number of tickets available will be locked in a couple months before the festival but is a floating number to keep costs down - no point hiring extra fields/staff if they're not needed. It depends on how you look at it but they haven't been near full potential capacity for many years now.
I am not entirely sure about using a general car park pass for Worthy View parking. It might be worth reaching out to the organizers directly to clarify. They usually have FAQs or customer support where you can get more specific information.
Thank You...