Why?
 

We bounce to the thrower on the sidelines & in the backcourt, but hand the ball on the frontcourt endline. Working with a younger official last night that asked "why?"

Just smack him on the back of the head. He'll stop asking dumb questions.

You're standing closer to the thrower there, the other players are closer, and a bounce might be awkward.

I was told by a veteran official it was to ensure we box in the players. Allow ourselves a good angle at the thrower-in and any pressure that might be coming.

I think I read this backwards. I was thinking why do we bounce the ball on the sidelines.

On the frontcourt, we hand it in because a bounce has more opportunity to be fumbled and since the defense is likely to be right there, this could lead to all kinds of messes.

Seriously though, speaking with Tony Brothers over the summer he said you guys do alot of things but have no idea "why" you're doing it. He said get a better understanding of "why" certain things are in place, so you can referee plays better.

Is this the only reason?

Yup, and on the baseline we hand it to the thrower because there are a lot of players around and you don't want the ball going loose.

When I gave this explanation, the bright eyed, bushy tailed youngster said, that can happen on the sidelines & b/c with pressure too.

I told him I'd get him a better answer...

It was explained to me that a kid making a frontcourt endline throw-in has enough to think about with his close surroundings. Catching your bounce pass just adds another thing. Since there's typically (though not always) less pressure on sideline and backcourt endline throw-ins, a bounce pass is acceptable.

There are a few on here that say their local association only allows bounce passes on sideline throw-ins, so check your local listings.

Just to cause trouble...
 

I officiate - among other things - girls' basketball in NY State where we use modified NCAA women's rules and mechanics. Under the NYSGBOA, here is the mechanic for administering frontcourt endline throw-ins on the table side of the floor:

If the throw-in is to be administered by the lead on the tableside half of the floor the lead administers the throw-in by handing or bouncing the ball to the thrower-in and then backing across the lane. This is being done to facilitate communication with the sideline

Now try explaining to poor new guy why, in NFHS, we hand the ball to the throw-in team for frontcourt enline throw-ins!

So you purposefully use a weak side lead? Defeats the purpose of having three, IMO.

That's so far from NCAAW mechanics that you could just as easily say "we use modified football mechanics"

To clarify, those are our 2-person mechanics. The 3-person mechanics are just as they would be for an NCAA Women's game.

I was taught it had to do with the amount of pressure. Pressure applied, hand rather than bounce in the bc and sidelines. Always hand on endline throwins in the FC. With that said here is the NF Basketball Officials Manual 11-13. Page 34. .

"T may bounce any sideline or end line throw-in (depends on defensive pressure)"

As to specifics; less likely to fumble. When handing the ball get out quickly and with distance to open up the view and proper angles.