Do you remember the case Israel used a million dollar missile to shoot down a uav several thousand dollars.
Israel has many choices in this case, but they make the most inefficient decision (economics).
I'm sure that if Ukraine had more options, using a missile that costs $100,000 or $1 000 000 to shoot down a $25,000 drone is not the right decision in the long run.
It's different between sending a missile to intercept something, Sure, you can use AA gun or even small arms to try to bring them down, but what if you failed and people died because of it, I mean sure, using multi-millions dollar missile to intercept drone like Shahed seems like a waste of money, but in term of defence, I will go with the thing that get the highest percentage of probability, because it won't make much sense by saving a few thousand or millions of dollar just for you to paid for people who died in that attack or the properties damage it was done by the drone.
On the other hand, you are talking about sending something to try and do some recon/intel run.
It is related to the vision of leadership.
There are 3 options here:
1: Use a hot air balloon
2: Using the plane
3: Using satellites
China has many choices, they can choose whichever way they feel it will work. Like Deng Xiaoping famously said "It doesn't matter whether a cat is black or white, as long as it catches mice.
China can use hot air balloons, airplanes, satellites, or a combination of all three. Depending on the situation, they decide which solution is best.
You probably don't understand why I put out that post.
First of all, these type of intelligence mission is pointless, as much as US sending RC-135 outside China, their intelligence value are REALLY, REALLY small, I am pretty sure China have their own EMCON strategy to limit their emission, now I don't know or don't want to speculate why China launch such mission, but for us, it's more or less just to keep Chinese or Russian on their feet and have them constantly need to come up and intercept our flight, this is more of a "present" thing than really intelligence gathering.
Modern day SCIF are almost (I said almost because I don't know SCIF capability now) immune to this kind of probe. They have everything set up just to make up for EMCON which mean most likely as DoD said, that balloon would not have anything to report to. The problem is, Chinese know that, as I point out that this is not the first rodeo for China. Which mean if I have to guess, they probably have the same aim than us sending up those RC-135. Which is to put us in our heel and show their "Present" but that did beg a question, why actually intrude into our airspace??
The difference between using Plane and using Satellite and using Balloon is that the former 2 don't intrude into US Airspace, the last one does, and as I pointed out. This is a major deal, if you want to do that (as in intrude into US Airspace) you will need to either prepare for war (again, that is an act of war) or you can't let the American know. Now, it would have to be stupid to think the US wouldn't know Chinese launch Balloon toward the US. Which only leave one suggestion. That the Chinese are either are trying to piss us off into an actual war, by launching a balloon illegally into our airspace. Or they are trying to see what our response. But then, if that is either way, why would China denied this is a surveillance balloon and apologise for the intrusion? So that didn't make much sense there.
Which make this more of a head scratcher. In the old days, when I was in Military Intelligence, we would probably just shoot it down near Guam or Hawaii or Alaska, but why this time we let them fly overhead and then make a big deal out of it.
My point being, I don't know why China launch these balloons in the first place and I don't know why DoD didn't just shoot it down and make a big deal out of it.