On A la Carte, Products, and Extras, the +/- quantity buttons on each item card are themselves the add-to-cart action — every click sends the updated quantity straight to your cart in the background, so there's no separate "Add to Cart" click required. A store can still show an explicit Add button next to the stepper on these three modules by turning on "Show Order Button on ordering system" in Client Config, in case customers find the automatic behavior confusing, but it's off (hidden) by default. Grab & Go behaves the same way for single-portion items — clicking + or - also updates your cart immediately in the background — but it always shows its own explicit Add to Cart button next to the stepper regardless of that setting.