depreciation is certainly a subsidy to capital, which is entirely unnecessary and distorts markets by upsetting the pricing mechanism. financial firms will happily provide upfront capital to any future profitable project.
"depreciation is certainly a subsidy to capital"
Only if you twist the meaning of "subsidy" to mean "any level of taxation less than 100%". Which may be what you mean, but (correctly IMO) isn't generally a popular POV.
it's a carveout and preferential treatment of (certain kinds of) capital. that's a subsidy, no matter the mechanism of return.