If I recall the details correctly they go something like this.
The chassis manufacturer does an alignment when the chassis is built and shipped to the coach builder. Obviously in the case of in-house chassis this is not the case.
When the coach body is added there should be another alignment check before delivery to the selling dealer since the loading of the completed unit could (probably did) change the alignment.
Most good dealers suggest that once you, as the owner, have loaded your unit with all of the stuff we tote around, filled our various tanks, water, fuel & LP that an alignment check would be a very good idea.
Here again, a good dealer with an in-house chassis shop could and should (in my opinion) offer or provide that last alignment check as part of the sales deal. Some can and do so, others aren't capable and seem to avoid the whole issue, thereby dumping the whole thing on the owner.
Right, wrong or indifferent, that seems to be the way this thing goes.
