They give super-precise descriptions for those things that they know almost all players agree on. We all know how a lighting bolt is supposed to go, so they straight up tell us in the description. But trying to regulate stealth, traps, tracking, negotiation, stuff like that? Everyone runs their games differently regardless of whatever the books may or may not say... so they don't bother giving a super-precise ruling. Basic ruling for all new players and DMs is what they give.. like for instance the "Influence" action they've highlighted... which is a fine simplistic system for those that need it but can be easily ignored or expanded upon by veteran players who already have their formatted rulings from years (if not decades) of playing.