IMO the most important factors of picking out a starter guitar are the scale length and playing action.
The scale length difference between the LP and Strat, for example, are not only major factor of feel but also sound.
A young person may prefer the feel of a short scale over a long scale and not realize why.
Another major difference is the angle of the neck. The LP and Strat again are good examples. The short scale combined with a tilted neck may be much more comfortable for a smaller person to enjoy playing.
The distance between the frets and the longer feeling neck (with no tilt) may not "fit" a young one and size of the person may or may not be reason...it can be just a preference.
Fretboard radius and fret size can be a major factors and also ones that are not easy to change if needed.
IMO everything else following those can be modified if needed. Some changes costing more than others so it's best not to overlook all of them in any price range.
Example; a radius of 9.5 may be much easier to play chords than a 14" and since the young player may not be shredding or a lot of string bending so the advantage of the 14" (or flatter) is of no matter.
Fret height and width can make a major difference to how the neck feels to the player and to a young one too...pointed out and comparing may help them notice and make a decision.
These differences can be found in every price range so knowing the differences and knowing how to explain and help the young one understand increases the odds of getting the one that he/she will enjoy playing for years.
When comparing and pointing out the major differences while the young one is trying them out has to help.
It's the beginning of learning to feel and listen to the instrument and may help the shopping experience with a perfect purchase. Again...JMO.