For a start, it's not I, IV and V, it's I7, IV7 and V7 - even if the m7ths are largely in the vocals until the instrumental chorus.
Why a 'blues'? Well, there are many points of similarity with the classic 12-bar blues. 4 bars of I7, then IV7 and V7 leading back to I7.
Interesting how many printed editions get it wildly wrong, both melody and chords.