I was going to agree with you, and then I got to this one and realized I do a form of this particular one. Often.
But it’s not sloppiness. Typing “I think you have that?” is an abbreviated way of saying “I sent it to you on the due date requested, and if you search your inbox, it’s in there — but I know you don’t use filters or folders and your inbox is a no-man’s land where all communications go to die, and whether or not you *have* it will be determined by how many emails came in after it ”
So instead, I say “I think you have it?” — to which the person will reply yes, I do, or no, I don’t. As per above, “no, I don’t” means too many emails came in after it and it’s lost in the inbox. So I resend.
The joy of email. But still, I wouldn’t go back to the time before it.