i Personally always saw most missions(with the obvious exception that are out of balance in contrast) not as a "way to make good money" but a way to make safe money(relativly safe). Missions provide you with a clear, and known, reward for a clear, and known, risk as well as known effort.
I can make more money by trading manually then by doing a procure or transport mission for example.
HOWEVER i have to spend some time prior to figure out what to trade where, and even with third party tools it may be unlucky do to outdated data(happend a few days ago, i almost made a 5 Million loss on a trade do to a outdated market and i had to jump far further then expected to sell for profit)
A procure mission only has me figure out where to buy the material relativly cheap nearby, thats still one point of research/failure, but its one less
a Transport mission has me do nothing but fly, it pays the least normally, but it is the most "direct" option
this obviously is using ships as a example, but on foot acts similiarly in taht regard