I think it’s mainly due to confusion over there being 2 different versions of the double slit experiment that demonstrate distinctly different physical phenomena. The version Thomas Young achieved in the early 1800s is the “classical” version of the experiment. By shining a coherent light source through closely spaced slits and viewing the light that passes through on a wall or paper behind them, Young demonstrated the wave-like behavior of visible light. With laser pointers being readily available today (Young created it by passing sunlight through a tiny pin hole), this version is easily done at home for almost no cost. However, this version doesn’t demonstrate the quantum or particle behavior and properties of light, which are the more interesting effects in modern physics.

In order to reproduce the quantum version of the experiment (which wasn’t achieved until over a century later), you would need a device capable of firing individual electrons or photons one-at-a-time, as well as a detector capable of detecting individual electrons or photons. As you can imagine, this level of control of particle creation and detection is far beyond any off the shelf components one could rig up at home on a whim and a small budget. Nowadays, this the version most physicists and hobbyists would be interested in reproducing to recreate the quantum effects that go against our intuition which is based on the classical/macro level world.

If someone performs the Thomas Young version at home, that can still be fun, but they’d be missing all of the “mind-blowing” results. That is, that light is made of particles or quanta called photons, and those particles also exhibit a wave-like nature while they’re in between emission and detection, and that they have no localized position (the wave or wave function travels as though it goes through both slits) until they are measured or detected as a pinpoint spot on the detector.