Should be there fits when you expect someone or something at a place but haven't checked yet. You'd bet on it, while plain is there asserts it.
Waiting for luggage? The bags should be there by now says you'd expect them.
When you're expecting someone or something to be present
Meeting a friend at a café? If you're guessing she's already arrived, write She should be there by now. You'd expect her, but you haven't checked.
Sending a package and tracking it online? It should be there on Friday fits when you believe the delivery date is likely.
Telling a colleague where to find a file? The report should be there in the shared folder works when you're confident but haven't looked.
Reassuring a nervous guest about seating? There should be space there for all of us lets you express expectation without promising.
One contrast to keep in mind: once you've checked or confirmed something yourself, drop the modal. If a friend asks Is my phone there?, reply Yes, it's right there or I don't see it. Writing It should be there after looking sounds evasive, as if you'd rather guess than answer. Save should be there for the cases above, where you haven't verified and want to say why you'd expect it.
Asking a repairperson when they'll arrive? If they promised a visit today, He should be there by noon understates it. Say He'll be there by noon, because the promise, not your guess, licenses the claim.
When should be there is too weak for your meaning
If the expectation comes from a promise or an arrangement rather than your own reasoning, should be there is too weak. A repairperson promised a visit today? Write He'll be there by noon. Should would turn his commitment into your guess, and that can sound like doubt about him.
If you're already sure because you've checked yourself, drop the modal. Telling a colleague the tickets arrived after you looked? The tickets are there in your inbox matches what you saw. Should be there would suggest you didn't actually verify it.