Raises a few interesting ideas. I welcome the idea of realism, and actively encourage the idea that a thoughtful pragmatic business mind will win over the general stock of shop models like... stack 'em and leave 'em, tt food, daily loot specials, etc. However I believe your time-frame isn't realistic when applied to Entropia.
In the real world a business has many factors to consider, and all sorts that were completely unknown until they occured. This means good plans turned sour due to small variation in funds causing bigger issues, and a general errosion of profits, such as discovering your taxes are more complicated and that now you have to lay off bob the junior bookeeper and take on someone more skilled. If you'd known to start with, then you'd have made a different set of choices, the path itself determines what your profits are. Some problems are cyclical and others are just ignored, so it takes quite a while for everything to come out and be counted.
It's not nearly as complicated in Entropia, I don't need to worry about my shopkeeper needing maternity leave, or worry about the fact she never signed a waiver to the working time directive.
The idea of changing the system from rent to profit % is interesting, but should be considered from the angle of how the current system benefits us and what we'd lose if it changed. I think it was assumed as a 'given' that closed shops are bad. They're not great news for the land owner or for the shopper, but for the proprietor it's only real implication is the loss of customer loyalty - which for many shop models in EU is pretty poor anyway. However with a shop closed, you've got zero outgoings - assuming you didn't take a loan off the local rl loan shark to buy the peds for your shop! MA even pay the electricity bill when the shops closed, since the malls were sold the lights have been on 24/7. So if the model was changed, the shopkeeper loses the ability to only open when he can make the most profit and attract a certain customer(s).
The flip-side of keeping a shop open to keep awareness high of the availability of your shop, is that if it's understocked, it'll get a name for that.
Another angle is the effect on other shop owners. A system where underperforming shops are closed benefits the open shop, as more trafic will enter your shop - by virtue of being open. Peds won't be spent in the the closed shop, and again you're more likely to see them. With a reasonably random distribution of shops closing and opening, we have two important idea at play. Crop Rotation - where someone else's closure means more success for you. Store Arangement - like when your supermarket puts stuff on different shelves. They don't do it cos they hate the shelf stackers, but they know something that I've tested to be true in EU too.
I've carried out a few tests, where I'd reduce certain items significantly, or in some cases make them available for tt+0 where they had a markup which either consistently exceeds 10% or it's markup is widely appreciated - such as oil, lyst, etc. The items that had price modifications, but remained in the same location, didn't sell. Move the item and it would sell - even when the markup is raised to a value that's only half of the previous discount.
Applying the same logic, a newly stocked shop will have shoppers checking the prices, a consistently open shop will have foot trafic that looks to see if anything
looks different.
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To put things into perspective of this thread, although I agree to your allusion that generally people underestimate the amount of thought and time to run a profitable shop. I think the far greater issue is that we simply don't have the numbers of people for the given infrastructure. We have impressive supply, matched with pathetic demand. A handful of people can craft the entire supply of weapons for a month in a single day; Clothes are far worse.
The systems in place are for skilling, not for paired crafting/selling. Even with 700k accounts, we'd still have balancing issues. But with a population which probably doesn't exceed 40k, it's just pathetic, we need ppl playing EU. I think EU has been built on the 'make it and people will come' model - just like Dubai...