So....you've basically described how the property market works today for the most part.
> What if we lived in world where real estate was not an illiquid investment, with extremely high barriers to entry?
It's not, about 70% of all people (in the U.S. at least) "own" or are scheduled to own their home. There's not an enormous barrier to buying property, you can even finance 100% of the property value in various ways so very little money is even required up front.
> What if the monies taken in rent actually accrued equity by some schedule?
This is basically how mortgages work. In general, some of the money you pay goes to the title holder to pay interest on the loan...this is effectively like rent except better, since you get some tax benefits for it. The difference goes towards buying the loan principle, which is effectively buying you equity in the property. Once the principle is paid off, you own all of the equity in the property.
> What if you could move at any point without losing your equity?
You can, you sell the property -- this is exactly how it works. The new owners effectively pay off your loan in one lump sum, you get pretty much the portion of the principle you paid off as equity, the organization providing your loan gets paid the difference. When you buy a new home, you can use the equity towards buying the new house so you have to finance less. In effect you move around your equity as you move around your house ownership. If you manage things well (it's up to you) at some point, you will own 100% of the equity in the property, in which case you will become the title holder.
Selling/buying a home is a bit more complicated than waiting for a lease to end and moving to a new rental property, but not by much -- it mostly just takes a bit of patience.
Let's look at your idea:
> Crazy ideas, I know ... but via example:
>1. developer builds a house, has 100% equity.
This is exactly what happens
>2. new tenant moves in and starts paying "rent", building up equity.
This is sorta what happens. When a person goes to "buy" a house, they typically engage a bank or some other finance organization who buys the home from the developer and then you pay your "rent" to the financial institution instead of the developer.
This enables the developer to turn over inventory quickly and continue building more houses rather than having inventory locked up for decades.
> 3. Costs for repairs and maintenance have to be paid per your equity percentage (so if I've accrued 20% equity, I have to pay 20% of the plumber's bill while I'm living there).
That's an interesting idea. Not how it really works of course, but an idea of shared ownership. To riff on this, if you default on your loan and the bank reclaims the property, they assume 100% of the maintenance costs. You'd need to control for people who want Cadillac everything throughout their house: Spanish tiles on the roof, gold plated pipes, top of the line appliances, etc.
> 4. When the tenant inevitably moves, they take their 20% equity, and are paid 20% of the next tenant's rent payments, while still paying 20% of maintenance costs ... this % of course decreases as the new tenant makes more payments.
I'm not sure I follow, if they take their 20% equity (to put into the next property) they wouldn't be entitled to receive any rent from the next tenant.
But if if a previous tenant leaves their equity with the property it sounds like then a person might end up with percentage ownership of tons of properties if they move around a lot.
Effectively your scheme describes that every property operates like a business with shareholders. Except the current executive of the property is whoever happens to move in. So you might end up holding equity in a property that somebody else burns down to the ground or uses it as a meth lab. But you would have no rights or controls over how the new tenant uses the property.
Furthermore, distribution of rents and collections and management of payments implies that there is a person who handles the overhead and management of the property, greatly depreciating the value of the property.
Not saying this is all terrible, but as an idea it needs some work. In the least it would greatly inflate the property management industry without providing much benefit to owners/tenants. In the worst it would require an entire rethinking of tenant/owner rights to use a property.