There's a lot more to the Mars Group than chocolate. Pedigree Petfoods, Uncle Ben's, Dolmio, to name just a couple of household names. They're absolutely huge, so I'm not at all surprised at the family's wealth.
It's an odd place to work (or was when I was doing consultancy work there on and off over about three years back in the '80s), with some definite 'family values' work ethics and stuff, which I'm sure contributes to their success.
Here's an interesting point - did you know that the UK operation (Mars GB) makes and sells more chocolate and confectionery products than the US? Chocolate bars as we know them were very much a British idea from the outset, so when one of the original Mars brothers (Groucho, I think it was ) set up the UK operation to make Mars bars it was a cutting edge industry.
Interesting point #2 The recipe for the Mars bars includes around 10% recycled Mars bars - if the end of the production line has to be left unmanned for a rest break they just let them fall onto the floor, from where they're shovelled up and fed back into a hopper at the start of the production line. But how did they make the first one, eh?
I don't think it's anything peculiar. I worked there for 9 years in 2 countries in South America, the US and the UK. In comparison with my other previous employers (Procter & Gamble, and Hilti), they are your run-of-the-mill multinational firm. Their core values as Quality (self-explanatory), Responsibility (it's about encouraging people to take calculated risks, and to be responsible for their actions), Mutuality (a shared benefit is a benefit that lasts, refering to the relationship between employer and employee, as well as between Mars and its suppliers), Efficiency (also self explanatory, and focuses a lot in doing what they know best) and Freedom (this one refers specifically to company ownership, and being free to make all their decisions, as they have no shares in the hands of investors). Their only quirk that I can think of is their "Good timekeeping bonus": a very generous 10% bonus, calculated on a daily basis, for every day that you're in the office on time.