I think it's because both Gale and Wyll come from loving, stable families and so they both don't get the "reminds me of home" option, which makes Okta take pity on you and give you a second bowl. Astarion was starved and only give disgusting food, so I assume that's why he has the option as well as the high elf option, same with Shadowheart. I guess they don't serve the yummiest food to Shar's disciples. I don't quite remember what got me the second bowl for Lae'zel.
Karlach calling Gale "ivory tower" when you chide her for encouraging Mattis to keep on grifting in act 2 as Avatar-Gale, might also be unique to him, but I'll have to check that. It plays into the same idea.
Githyanki have the option to be curious about Faerunian food and get a second bowl that way, so I guess, Lae'zel can use that answer.
