I found a relevant post and NVIC notice. What was once an unlimited oceans license, has been reduced and restricted to work inland or on 200 tons or less. Like many teacher programs, they need to provide a viable path for those looking to start or return to the mariner pool. Months of school and expenses close to $20k for courses only, not to mention the days and travel, etc. Companies are not paying for training and wages do not make up for it, hence, the crew shortages.