Why is the prohibition in matters of etiquette understood as reprehensible (makrooh) and not as strictly forbidden (haram)?

The default rule for a prohibition is that it signifies tahrim (prohibition leading to sin), unless there is an indication that changes its meaning to karahah (disliked but not sinful). Many scholars have considered the presence of a prohibition in the context of manners (adab) as an indication that shifts it from tahrim to karahah. This is because many prohibitions in this category have garnered a consensus that they are not for tahrim, and the majority of scholars have interpreted many of them as signifying tanzih (disliked in a way that avoids sin).

It is possible to differentiate between acts of worship (ibadat) and manners (adab). Orders pertaining to acts of worship are for wujub (obligatory), and prohibitions in them are for tahrim. As for manners, orders concerning them are for guidance (irshad) and not obligation (ilzam), and prohibitions in them are for karahah and not tahrim.

This distinction is prevalent in the discourse of many scholars. Examples include the prohibition of istinja' (cleaning oneself after relieving oneself) with the right hand, the prohibition of eating two dates at once (from a shared plate), the prohibition of walking with one sandal, and the prohibition of eating from the top of the food.