You need also take into account that some characters start with better armour and weapon.
So price of recruiting also cover cost of their equipment. So difference in cost between beggar and sellsword is lower than you think.
Personally I think that some backgrounds should be even more costly to recruit.
Hopefully when reputation/fame/renown system will go on there be more options for recruiting new characters.
#nobles or professionals will join only company that have high reputation.
#good characters will only join company who have respectable reputation.
#criminals and bandits would have very low cost in money(or cost nothing at all) but filling your ranks with them will give you bad reputation points(as your company will be seen as safe heaven for outlaws)
Also I really hope that background system will be expanded.
Now character have single background with some possible traits tied to it.
What I would gladly see is something like:
#character class like royalty, high nobility, minor nobility, men-at-arms, free men, serfs, wild men(clansmen), patricians, citizens, commoners, clerics
#then based on their class they get profession
*for example high nobility character could be be a family heir, knight, noble adventurer, squire when minor nobility could be knight, squire, sellsword with but with lower tier equipment for the same professions
#some professions could be tiered so experienced sellsword would have little different bonus statistic than young one.