are you allowed to eat outside of the succah when on an outing?

a person is allowed to eat while on a trip because of the heter of Teishvu Kein Teduru! This means you only have to sit in the succah as much as you would sit in your house. Since when living in your house you would not refrain from going on a trip and you would eat on the way, so too you are allowed to duringn Succos as well when you are living in a Succah.

My question is what about when you go to a themepark or the like? Why does no one eat outside the Succah? If you were living in your house you would eat in the themepark so why not now during Succos?

See the sefer that Reb Elyashiv brought out on Shas, called HoArois and in Succah 26 he brings from Reb Moshe that one cant eat outside the Succah and he says it is fine!

I have always been brought up not to eat but may yet eat this year based on the Reb Elyashiv in Danny's answer. But I'm still scared though!