"I know it can't be depreciated, but some how it feels like it should be deduc"

You are confusing cash flow and expense.

Your taxpayer invested in the land. Their money still exists. It is right there in the land. There is nothing to deduct, because nothing was spent. When you spend money (an asset) on land (an asset), nothing changed except the asset type.

That's why it is not deductible.

Depreciation is "consideration in the tax code for wear and tear until that asset wears out" which is why land also is not depreciated. As noted, there can be loss due to destruction of value or existence of the land (flood, landslide), and any separate parts (buildings, crops, etc). But the earth abides, Dude.