They can and do but it's much less reliable. Births and deaths are systematically recorded, and fertility rates are shaped by comparatively stable factors like education levels, access to family planning and gradual cultural shifts. Mortality rates follow similarly predictable trends.

Whereas migration flows are heavily influenced by sudden events that are difficult to anticipate, like economic crises, political instability, wars, natural disasters and so on. The data is less complete too, for example unauthorized border crossings will not be recorded officially in cases where these are undetected.

I'm sure that strategy was used until open xenophobes got into power and wanted to nurture the fear of their supporters by artificially raising the urgency.

> Let's stick with the whole "adaptive ecosystem" model, rather than a "government planning" model

1. Every "adaptive ecosystem" has limits.

2. Without proper government regulation, which includes some "government planning", an "adaptive ecosystem" cannot and will not exist.

3. Abusing 1 and lacking 2, things not only don't "turn out better every time", they turn out really bad every single time.

With that said, abusing immigration enforcement in order to habituate disregard for due process is deceptive and over the limits and it leads to worse consequences than immigration itself.