Does Apple check to see that my IPAD data is removed after trade in?

Before trading-in your iPad, for your own peace of mind, you should always prepare the iPad for disposal. This process will perform a crypto-erase, fully wiping all of your data and personal information from the device:

What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support

If trading-in with Apple - and not a third party - you also have assurance that the device will proceed through Apple’s precesses to ensure that the device is fully cleansed of all data. Should you trade-in through a third-party, you don’t have this added assurance.

Spedprof wrote:

Does Apple check to see that my IPAD data is removed after trade in?

As stated above, prepare your iPad yourself. Use the Apple-documented procedure linked in the previous reply.

Your iPad should be using a robust passcode, too. Your passcode is central to all of your iPad and even your Apple ID privacy and security. Skimp on your choice at your peril. This should your iPad be lost or stolen or damaged or dunked. Should you be unable to reset it for whatever reason, as well.

If you followed the Apple instructions, there is nothing left on the iPad. Nothing left of yours, that is.

Exactly what Apple does here has not been documented in any detail, though they’d be foolish to even look and foolish to assume that the device is already erased.