Having never propped a screen up in front of a baby, I'm not needing to defend my own parenting choices.
However, I'm returning to the thread to award gold medals to those pps with Olympic-standard skills in the high and long jump. It is a truly enormous leap to link parents who use a screen in moderation, including as a distraction for a short time in a restaurant as in the OP, or need support, or aren't as educated, fortunate or monied as you, to those who neglect, abuse and kill their children. It is also disrespectful to the experiences and memories of those real children.
Remember, we only see a snapshot when we see something like the OP saw in the restaurant. We don't see the other 23 hours or so of their parenting that day, the rest of the week, the month, the year or the decades. I am sure I have made mistakes in public and in private during my many years as a parent. Apart from at the extremes where we all need to sit up and take notice and action, we really shouldn't judge, look down on and mock, because we are not walking in the shoes of others.
If you can't help, accept or understand, then don't hinder - just look away and go about your own business. Parenting can be a tough job. We all do it differently and we all need support.