Orvis 10' #5 Recon =108 grams. Shakespeare Agility2 10' #5 = 114 grams. The end of the reel seat on the Shaky is solid bar stock (I know because I drilled it out to fit a butt) and is probably the reason for the extra few grams static weight. So hardly twice as heavy and with the extra few grams being behind the reel.
I suspect that cheaper tackle is not even considered or tested by many, on the assumption that cheap is nasty - which the latest Shaky offering, certainly is not.
When you build rods you start to see how the balance is far more important than the weight.
A super light, tip heavy rod will feel heavier than a well balanced, heavier rod. I built two demo rods of my 9 weight pike fly rod, one with a standard Fuji "pipe" reel seat which is very very light indeed, and one with a salt water proof Struble titanium seat that was heavy. On the scales the titanium seated rod was just over an ounce heavier. In the hand, people though it was the lighter of the two rods. This was because it balanced perfectly.
In general, the more expensive gear tends to have better components, be better balanced, and produced in countries where labour costs are higher. This accounts for the cost.
In general cheaper rods are mass produced, have cheaper components and are made in countries where the living wage is far lower. This accounts for the savings.
In some cases companies use identical blanks but the cost of the finished rod can be vast because of the above.