[BleedOrange11]

There are many other variables at play here. The difference between active and passive is usually negligible. Firstly, what do you constitute as good 3D visuals? And what do the filmmakers constitute as good 3D visuals, and did they achieve that? An image with strong 3D depth and volume? An image with pop-outs? An image that doesn't give your mother a headache? You don't say why she gets a headache. There are many possible reasons, and she may not know.

The modern way of viewing 3D images on a flat, planar screen, usually with glasses, causes an accommodation/convergence issue that may give inexperienced viewers a minor headache, caused by fatigue of intrinsic eye muscles accommodating and converging at different locations simultaneously. Assuming healthy, normal eye musculature and binocular vision, these types of headaches go away completely with practice looking at 3D. This is basically unavoidable until holography is realized.

Large theater screens are less bright than backlit televisions. In general, it is more eye-straining to look at a dim image than a bright one. This is a big reason that people say 3D looks better at home, and it has nothing to do with active or passive or even the shape of the 3D.

Unlike at home, it is impossible for a theater-goer to manually alter the calibration of a theater screen. Sometimes theater environments are improperly calibrated, and the staff is incapable of correcting them. This can be any issue from 3D image alignment to screen brightness/contrast, color balance, audio volume, not turning off the house lights, handing out the wrong glasses, or even presence of noisy bothersome patrons. 3D is just one more variable that can go wrong. This is the other major reason people prefer to stay at home.

Theater screens are larger than TVs and most home projector setups. A larger screen will allow the viewer to sit further away from the screen, which mathematically increases the roundness of the 3D image. Most people like this aspect. This is the reason that people prefer to go to the theater. Theoretically, seeing an image on a big screen should look better, or more cinematic, more majestic. It even "increases" apparent 3D depth.

Additionally, depending on the 3D parallax values, sitting too close to a 3D image on a large screen may result in issues fusing the 3D image, causing eye strain. This can usually be resolved by sitting further away, which effectively makes the parallax values seem smaller (and the apparent 3D depth larger). Never sit in the front row.

Assuming optimal calibration, nice projection, nice viewing environment, 3D looks much better on a theater screen for me than my at-home 42in TV or VR devices. The problem is that I can't always trust my local theaters not to have brightness issues, projector alignment issues, or audio that's too loud. It's also a major pain getting in traffic near the best theaters (due to construction), so sometimes the expense of time, gas, admission, etc. is just not worth it. I'd rather purchase a Blu-ray 3D that I can own and re-watch in my own environment and on my own equipment that I control.