I'm not sure what the fluff is for why Arcane Tricksters and Eldritch Knights don't have the ability to learn spells from scrolls, but they don't in the tabletop either despite being Intelligence casters and explicitly described to be practicing bits of wizardry by default.
Eldritch Knights are described as 'committing [spells] to memory rather than keeping them in a spellbook'. Arcane Tricksters don't get such a description but we can assume that they have a similar thinking behind not learning from scrolls.
Remember that copying spells from scrolls is actually inscribing them into a spellbook. If you don't have that spellbook then you cannot copy a spell into it. No spellbook, no 'learning' from scrolls.
