4. Spider-Man doesn't use a voice-changer and no one recognizes him
While we're talking about the things Spider-Man inadvertently does that could risk revealing his secret identity, we have to ask an important question; how does nobody recognize Peter's voice when he's wearing the costume? It's not like he uses a voice changer or anything.
This same problem could apply to many heroes, but some adaptations acknowledge that and, better yet, do something about it. We all know how Christian Bale had a signature raspy voice whenever he wore the cowl in Christopher Nolan's Batman movies. Furthermore, Zack Snyder gave Ben Afflec's Batman an actual voice changer in Batman v Superman: Dawn of Justice. And who can forget when Tony Stark had a voice changer in the Mark 3 suit as well before deciding to reveal his identity to the whole world?
Even Spider-Man: Homecoming saw Spidey use a different voice when interrogating Aaron Davis, and then quickly forgot about that concept. The problem is many people close to Peter Parker always get caught in the crossfire between Spider-Man and his archnemesis. If Mary Jane, Aunt May, Harry Osborn, or any of Peter's friends hear the web-slinger talk with Peters's voice, that would surely give his identity away. Coupled with how the teenager always disappears when there's trouble, and how he takes great pictures of Spider-Man, it should be easy to put two and two together.
It still baffles me how in The Amazing Spider-Man 2 Harry discovered Spider-Man's identity by watching him being protective of Gwen Stacy, and not by recognizing his voice much earlier in the film. I guess some things just don't make any sense at all.