Nor should they be. The world is far too complex for that.
How much should a loaf of bread cost when the wheat is grown in small, hand-tended with bovine- or equine-powered simple plows plots of land, the wheat is ground on large horse- or water powered stone mills, and the loaf is baked in hand-tended wood-fired ovens? How much should it cost when the wheat is grown in large, machine-tended, chemically fertilized and protected huge tracts of land where the per-pound cost of the grain is way, way less, the wheat is ground in modern mills, and the loaf is baked along with 50,000 other loaves in machine-tended gas ovens?
Modern steel (a huge improvement) vs. fantasy steel? A leather belt from the hide of rarely-slaughtered cattle vs. the leftover hides from the modern beef industry?
Etc., etc., etc. There's just no even remotely realistic way to compare one to the other across every area that technology and human desire has touched. Most importantly gold today isn't pegged to anything but what people are willing to pay for gold. Contrary to what pretend investment analysts will tell you, gold has lost a lot of value in the last 30 years and is a terrible investment.
Heck, a gun out of a guy's trunk cost a much smaller percentage of a household's income than a fantasy sword in a fantasy household, while a fantasy-type sword today costs much more than that gun.
Money in the past, especially metal coinage, was generally worth what the metal itself was worth, but in today's world money is worth a portion of a nation's ability to generate wealth. All of the concepts are just too different to compare.