They don't want the business. They could offer a sort by English menu button with virtually no programming effort but they don't.
You can use their online site with Chrome and Google Translate the page, although logging in to see the prices is annoying as you must use a phone access code each time. It is the easiest way though.
https://food.grab.com/th/en/?utm_source=grab.com&utm_medium=referral&utm_campaign=hero-banner-food-product&pid=Grab.com&c=hero-banner