Why does Adobe Lightroom not automatically update the picture file when they are changed in the program?

Answer 1

Lightroom updates the images in Lightroom by tracking and maintaining the adjustments to the original image, but NOT changing the original image at all.

This is a good feature and protects your original images.

So, if you make changes in Lightroom, then go look at the file using another program, you will not see any changes to the original file.