I have been in the same position as the OP. Bags never made the flight, one has to wait until the conveyor belt stops, then typically find an airport contract worker (not an airline employee) to verify that no more bags are coming out. I would fully expect for anyone in customs to tell a PAX that they need to wait for their bags until there are no more bags coming out. Leaving to make a connecting flight is typically a no-no (but not sure what the consequence would be). At that point one needs to clear customs and deal with the issue at the baggage recheck. Which recently IME may not be staffed with an airline employee. Given the immigration, customs, and bag recheck I would not expect that to take more than 90 minutes on a bad day.

So my only question is what was the ticket and the connect time? Delta will sell tickets that do not meet the MCT. So for the OP would you fill in the blanks. How much time was there between flights? Were all the flights on one ticket? At this point where is your bag?

As for compensation. The issue is that sounds like you took the bus on your own. Before doing that did you talk with anyone at the airport? That would help making the case that the airline should pay for the bus. As for the 8 hour wait and finding out there were no seats. All hindsight but it pays to double check. I would have probably said screw that wait and taken the bus but understand why you would not.