Loyalty vs Tax rate

Here is the afterthought:
I do understand that loyalty depends from number of things like taxes, number of troops, buildings, etc. Also, morale of troops looks like depends from current loyalty level.
Question is: if in the same province I'll produce an unit when loyalty is 200% and tax rate "very low", and then another unit when tax rate is "very high" but loyalty still 200% (because of other factors) will be morale the same in both cases?

morale of troops has nothing whatsoever to do with provincial loyalties
when building units morale is constant, defined by unit type with bonuses coming from certain buildings ( churches for example)

Then why many people lower tax rate before produce units. (I've seen this in many topics)?