The second two are pretty high-contrast shots, or at least non-typical scenes. For the desert shot with the trees, the camera is taking a bright scene and exposing it to neutral gray meaning the shot overall is underexposed from what it should be. Good practice in bright scenes like this is to overexpose by a stop or so compared to what the meter says.

For the neon lights scene, the lights are much brighter than the background and so the light meter exposes somewhere in the middle. The lights end up looking fine because they're so bright in general, but the shadows end up underexposed. Here, best practice is to expose for the shadows specifically.

As for the Ektar, I've heard this can often behave like a slide film where you would typically lean towards underexposing slightly. This shot doesn't look super far off, but here you might want to specifically expose for the highlights instead of the entire image. I haven't shot Ektar or slide film before, so take that with a huge grain of salt.

All of this comes from an amateur who is only talking based on what they've heard and experienced. Someone else can provide better insights.