Oh brother, your going to be in for a rude awakening if you go to any of the
Disney parks. And their policy is ABSOLUTELY NO OUTSIDE FOOD ALLOWED in the park, (At least that was their official policy back when my parents used to take my brother and I as kids.) Anyways, the price on the Surfliner is not any different really but sellout and early closure of the car is a common thing. Many times, there is usually a long line even snaking up the stairs. As others have said, time of day also matters. Beer, wine and liquor sell out seems to be a common problem on the Surfliner. Well a problem for me, since its all gone by the time I get down there to get one.
That is absolutely false. Unless this was a policy before the first time I visited in 1980 (U.S. Navy boot camp graduate) I carried a sack lunch I placed in a locker and ate sitting under some awnings by the (now gone) swan boats. In 1991 we started taking our son there almost annually. When we didn't stay on site we always packed a lunch and ate it in an out of the way place. We still purchased our drinks there. As far as the comparison goes, I think that the pricing at the Disney and Universal Studios counter service restaurants is very similar to Amtrak prices. I would, however, say that the quality at several Disney (and at least one Universal Studios restaurant - Monsters Cafe) counter service options are better. Of course you don't have the ambiance of the moving scenery outside your window either - but you can be entertained by
Sonny Eclipse at Cosmic rays in Tomorrowland. Cheesy, yes. But 23 years ago my then 3 year old would sit mesmerized during the show.
Sadly though, I will admit that the little perks you you to expect from a stay at WDW are slowly being whittled away by senior management in a cost cutting quest. Pretty much as you've seen happen on Amtrak with the sleeper car amenities.