Why were these photos rejected?

A simple fast look into your first image shows many rendering errors: 

THe other pictures are not better. I'll let you the joy of detecting the issues there. You just need to look at 100%.

Rule #1: AI machines make lots of mistakes.

Rule #2: AI generators are not equal. Compare services to understand their various pros & cons. 

https://www.pcmag.com/picks/the-best-ai-image-generators#

Rule #3: AI is a tool, not a replacement for genuine human talent.

Rule #4: AI won't make you rich. The cost in money & time to create/edit commercial quality Stock images often exceeds the 5% profit potential. 

Good luck. 

The AI drawing errors are easy to spot. You must zoom in and carefully inspect every area of your images. If you can't edit out the flaws, move them to the trash bin.

Rendering errors. Lack of symmetry.

These are not photos. They are AI generated images. Photos are made with a camera. 
All of your images have rendering errors. The last image has artifacts around the car. 
Here are some of the mistakes I see in the first image: