Airspace incursions are a more or less legal (definitely closer to the less side) way of forcing an opponent to incur attrition. Just fight hours on planes is extremely expensive and somewhat dangerous. So forcing jets to scramble causes the other side to spend money you might be in a better position to absorb.
ADIZ is not a nation’s airspace, which is actually part of it’s territory according to international law. In fact ADIZs have zero basis on international law, neither Taiwan’s nor China’s nor the USA’s.
With that in mind it should be no surprise that ADIZs are way bigger than a country’s airspace (which matches it’s territorial waters). Taiwan’s extends over mainland China. Of course they don’t report on Chinese planes flying over China but even the median line is way further out than the 12nmi of territorial waters/airspace a country is entitled to.
Of course China also arbitrarily claim to have an ADIZ as well as arbitrarily claiming the whole strait to be internal waters thus their territory.
The CCP arbitrarily claims Taiwan is their territory, so we really shouldn’t take them seriously about any claims they make
Taiwan also claim they are the rightful government of the territory of the CPR. Nothing arbitrary, the states are the offspring of two opposing sides in a civil war. For decades Taiwan even kept claiming Mongolia as their territory.
they are also testing to see how close they can get before provoking a response.
They might even be trying to provoke a shoot down, to justify some other action they have planned.
It’s a giant game of I’m not touching you, where both sides have nukes (Taiwan via the US, but still)
I mean just shoot rockets from ground, way faster and easier.
But those aren’t reusable, so would cost even more
Neither are the enemy planes you take down
Oh, your advocating just full on shooting them down rather than turning the missile off when the other plane turns around? That’ll escalate things super quick. Tiwan doesn’t want to go to war, which it why China can do this.
So China flies planes over its own land
If it was their own land, they wouldn’t be doing this. Check and mate.
They don’t own that land since 1895 when they conceded it to Japan