Because on a polyp/head basis they are not more expensive. I just had a beautiful zoanthid I purchased from reef2reef delivered today. I paid $65 for 50+ heads a little more than $1.00 per polyp. I also received 6 zoa frags of about 10 heads each that I paid $25 each for. I liked them and I am going to see if they will grow together into a colony. An experiment. But purely from a cost basis, the bigger piece is a better deal. I have a really nice sized acan I purchased from Austin Aqua Farms a couple of years ago. Last week when my rock stack collapsed part of it got covered by sand and died. But just a small part maybe 2%. If it been a frag it all would have died. I would rather go to LiveAquaria and pay $129 for a 4-6 inch favite than $30-$60 for a 1 inch frag. But that's me. You are welcome to do whatever you want.
Granted I am old and not as smart as I used to be. But when the conventional wisdom is, "the hobby can only get frags because of scarcity," and at the same time there are over 24,000 corals listed on Ebay, a vendor in this thread claimed he frags 1,000s of corals every month and there are literally 100,000s of thousands of corals available on the internet, I have to question the conventional wisdom. Walk into Ferrari Beverly Hills and you will pay the sticker price. Why? BECAUSE IT IS A FERRARI!! There aren't 100,000s out there. But google acroporas for sale and you'll find 1,000 or more for sale at any one time. THEY ARE NOT SCARCE! Yet somehow the online retailers have successfully convinced the hobby that they are scarce and valuable. Trust me on this, at some point someone is going to come along and Amazon the online coral trade. Completely disrupt it. The bubble WILL burst and prices will come down. I wouldn't be surprised if there wasn't someone right now farming corals on a 5-10 year plan to blow up the market. If I was younger and more talented I would take a shot at it myself.
1.00 a Polyp great.
But what about a Hardcore Collector like myself.
I have over 130 Different Types of Zoanthids.
So what you bought I either have or don't want.
If I said I am only buying cheap frags or colonies I would never be able to buy another Coral since I have all the cheap ones.
So I am willing to pay more.
I like Most people started buying cheaper corals but once you get them all you start buying more expensive ones.
Some Corals are common and/or uglier so they cost less.
Some Corals are Rarer and/or nicer looking so people will pay more.
It is supply and demand like others have stated.
You don't seem to realize that.
There may be 1,000 of Acros but there are only so Many Walt Disneys. They are rarer and more colorful so people will pay more.
With Your Logic Cars are Common so they all should cost the same.
Why are you not Arguing why the Ferrari is so much more than the Ford?
It is because it is more desireable.
Same with Coral. Some are much more desireable than others.
And it looks like you enjoy common corals (Which is fine). So why complain about all the named rare corals (You don't want them anyways so this doesn't affect you).