Because lords want to charge extortionately high food prices. The system let's them charge up to 50, so they feel they should be paid 50. Sales outside the realm on Dwilight are pretty much exclusively done at a rate of 50/100, or very close to that. And to get that requires some kind of inter-realm agreement.
On EC, I do occasionally see some open sales, but very rarely for under 30/100, mostly nearer to 40/100. But people won't pay any higher than 20-25/100.
Like I was saying before, gold is so plentiful that lords have little or no incentive to sell, except for patriotism or a desire to help the realm. This is especially true for lords of high food regions, because they are also high gold regions, too.
50 is
not extortion nor is it too high. On Atamara when food prices weren't capped, I constantly bought around 55-60 from one realm and sold at 60-70 in another. It's the Margraves who think that because they have a city, they deserve the food either free or basically free for 10-20, who are complaining.
If gold is so abundant, why aren't all buy offers everywhere 50/100 all the time? I don't think "lack of incentive" is the problem here. It's the prejudice that "Lords and filthy rich and hate doing anything so they deserve nothing" attitude that almost all Margraves/Dukes have.
As Scott said, if a Margraves post as many 50/100 buy offers as they need food and then go away and then repeat when they're filled,
then they have a right to complain the system is broken.
