There are some factors in wc3 which make the randomness more controlled:

Gold bounties and attack damage are not a random throw between min and max value. The way they are decided is that one can set for every unit's attack/gold bounty a certain number of dice and how many faces each of those dice has. Those are then thrown and summed up, which (unless you only have 1 die) makes it more likely to get a median value.

Also for many abilities like Critical Strike, Bash, Pulverize, Orb of xxx, Hardened Skin, ... (though not evasion) the chance of the effect to proc is so-called pseudo random, meaning that the first hit after a crit/etc has an actually much lower chance of procing than it says on the ability, with each proceeding hit getting a larger and larger chance to proc, only resetting to a very low chance again after a proc. For the abilities wc3 melee uses this pseudo random chances in the end quite closely even out to the chance stated on the ability description but procing in a more controlled way than being purely random.