If players could not see through walls with crouch/sit/shrink/gnome/etc, the value on items like with would be much less.
the cheaper option is
https://wiki.project1999.com/Stalking_Probe
The best part about stalking probe in my own personal experience is it can be used in classic exploits combined with spells to manipulating your character's position in the world. Like how logging out does.
*everyone's ears and eyes just turned towards baler*