Originally Posted by
Often1
This is incorrect.
US law is clear and has been since 2011.
The base baggage allowance for the marketing carrier of the first segment applies to the entire ticket. This does not apply to waivers for status, credit cards and the like and a carrier is free to exceed the allowance.
Without knowing the marketing carrier of the MAD-AMS segment, it is impossible to tell for sure, but it appears to be one bag. That allowance is guaranteed for the remaining segments. Anything above that is at the discretion of the operating carrier and that is why there are some segments with a second bag included and some not.
OP clearly posts that it is DL. The DOT rule doesn't require the same allowance on all flights. It requires that the allowances of the same airline apply throughout. Just because policy allows for one free bag on first flight doesn't mean the next flight also must get one. Instead the same airlines allowances must be used.