Being a forum for hackers liking Titleist products, no one here has great insight to marketing decisions. Titleist includes the number at the same time as adding the script to be sure it is correctly located. So all the custom numbers are all generated the same way as 1-4. They then send them in quantity to a custom packaging area for either boxed only by custom numbers or for addition of other customized additions.

There needs to be a marketable quantity to run them. Similar to why yellow urethane balls do not get custom numbers. Not enough demand to run small batches of custom numbers to warrant limiting throughput. Guessing not a lot of demand for zero over double zero.