The first and most basic thing you must know about economics

The world simply will not make sense if you do not grasp the first and most basic thing you must know about economics. Which is that incentives matter.

What the incentive is, what the action or activity is, those are things which can all vary wildly. Whether something acts as an incentive or a disincentive can change too. But it really is crucial to understand that whatever else might be going on, incentives matter:

In 2004 the New Zealand government introduced legislation banning anonymous sperm donations and preventing donors from receiving any payment for their services.

Donors in New Zealand have minimal costs covered (such as travel to the clinic) but are not compensated for their time, which after rigorous medical testing and counselling, can be significant.

Under the new law, the sperm donor must also agree to being identified to any offspring when the child turns 18.

A decline in sperm donations following the introduction of the legislation coincided with a sharp rise in same-sex and single women applying for donated sperm.

It's not difficult to predict is it? On the application side the greater controls mean that fertility through donation is more desirable. On the production side the greater controls make production less desirable. Note that there's no money floating around this system but we've still got a change in demand and a change in supply.

And given that we've not got a price that can change to balance them we've got a mismatch.

Incentives really do matter.