Though those may contribute to yellow urine in some cases, I think you’ll find that they are not the primary cause. Riboflavin (Vitamin B2) is a potent fluorescent yellow ("-flavin" is from the Latin for yellow) used as a pigment and food coloring.
Vitamin A is a fat soluble vitamin, and AFAIK, is generally stored in the liver and other tissues, and is not readily excreted per se. There are several conditions that can cause increased direct excretion of Vitamin A or its conjugates, such as infections, especially urinary tract infections but generally it must be slowly metabolized to smaller molecules or complexed with fatty acids, and would not add appreciable yellow color to the urine [I would expect these byproducts to be excreted through the bile into the feces, but I do not recall having specifically read that this is true). Body storage of Vitamin A can be medically significant, because it is toxic at high accumulations (as is Vitamin D, the other major fat-soluble vitamin), and can cause complications if high doses are taken early in pregnancy
Beta carotene, a precursor of the retinols and retinoids, including Vitamin A. The retinols include the primary visual pigment (hence the name, from “retina”, and one of the signs of vitamin A deficiency: night blindness). It also plays a role in the bone and tooth formation, and its derivatives play a role in the control of cell division. This last is important because they can actually be pro-carcinogens (helping to cause cancer) in some cases [e.g. beta carotene supplementation decreases cancer in nonsmoker, but increases it in smokers; topical Retina-A creams are used to heal cosmetic skin damage, but can help cause skin cancers in high-risk individuals – which is why it’s only available by prescription]
Beta carotenes only became a part of the multivitamin mix in the past 10 years or so, after its protective efffects against cancer were widely publicized (and since they aren’t the best choice for everyone, not all multivitamins include them even today). However, yellow urine caused by brewers yeast (a common early vitamin supplement) has been noted for over 100 years, long before today’s multivitamins, and especially beta carotene enrichment could have been a cause.
On a purely personal note, though I haven’t conducted specific tests, I have not noticed that carrots or tomatos [rich in beta carotenes] appreciably color my urine. Reports from others would be welcome, however, since I am avoiding starchy foods right now, and root vegetables like carrots are rather starchy.