I'm aware that a lot of ones bought in supermarkets are actually pretty poor anyway. The form of the mineral they have chosen is cheap rather than readily absorbed so you aren't going to get most of it. The more expensive ones use different chemistries so the minerals are better absorbed. You need to pick the right ligands for things like Iron, otherwise you are just sucking a steel bolt and hoping to extract the iron. No idea if this is the same for the vitamins.
Also 100% RDA is typically a minimum not a maximum. If you take into account the fact not all of the tablet content will be absorbed and utilised then the likes of Centrum which contain 100% RDA won't provide you with 100% RDA. The Biocare ones mentioned above often contain something in the region of 3000% RDA to ensure you get what you want out of the tablet.
Sounds like a vitamin salesman's pitch.
WTF, is there such a thing as a vitamin salesman.
If you buy something, someone is selling it. The person seeling it has a vested interest in shifting it to make as much money as they can. The guys making the vitamins on an industrial scale will almost certainly employ people to sell and market their product. So yes there are such things as vitamins salesmen. They might not work like a double glazing man knocking on your door but they still try and sell the stuff by working out how to make people want to buy it. In this case convincing people that they need it for good health.
How many people eat a decent diet? Not too many me thinks, it's also hard to get adequate vitamins from diet because of so much refinement along with additives especially preservatives. Most people who do not train hard probably do not need vitamins although they are usually the ones with bad diets.
Interesting that you mention preservatives. I used to work in the food industry as a development technologist (I'm a chemist by degree) and the there is a huge amount of vitC added to things as a preservative. Plenty of fruit based products use it as it stops the product going brown (anti oxidant you see).