remotely shutdown iPads....Please?

If Apple can, then why can't we?

Because... they are Apple? They probably have dozens of tools and MDM functions that we don't have. Its their show after all and there is nothing that says everything they can do with their devices we should also be able to do (though it would be nice)
Maybe someday these functions will trickle down to us regular folk. I'm sure many of the capabilities we have today with iOS started out as something only Apple could do and eventually made their way into the public space, but I wouldn't always count on that.

If you or your school or business is part of the developer program, you can make a screen lock app and push it out in house.

a screen lock app wouldn't really help. you can do that already with casper anyway. but the ability to actually power down an iPad, not just put it to sleep, would be insanely beneficial

How would you wake it up, then?

For our purposes this would be so helpful in 2 scenarios:
When prepping large numbers of devices it would save so much time to be able to grab 30 or 60 devices and shut them down with a click rather than holding down each button and then swiping.....and so preserving battery life until deployment
Another scenario: as we have carts in buildings and are still rolling out wifi Density in phases, sometimes we hit saturation when a MacBook cart rolls in for use where an iPad cart is sitting. If we could shut the ipads down without pulling each one from the cart, that would be awesome. Of course we advise staff to have kids shut them down when not in use but that is not something that can be or is supervised....

There's a lot of things with managing iOS devices that would be helpful to have, but they're all out of JAMF's control. They control what Apple lets them. Talk to your Apple reps, not that it will do much good probably.

I've been asking for a supported shared device model beyond Configurator for years now with only the same response something may be coming.