Yeah not sure why that changed, when I was a kid you could only get sparklers and small stuff that stayed on the ground. Today I could get everything for a near-professional show if I wanted to spend the money.
It's really dependent on your state laws. My state allows fireworks, so you can get most things but they are very limited in size and explosive content.
What it amounts to is that most cities/counties don't enforce their existing laws in this area because people would have a shit fit, and they would arrest so many people that it's kind of impossible.
Something something banning things doesn't really work to do anything but make criminals out of every day people.
A couple of years ago my brother got some flat triangles from a guy on the side of the road. First thing I've seen in years that was like an M80. We put a flat soccer ball over one, and it went 50 feet in the air. Very fun.
Not even close.
A military M80 [0] is ~5g of flash powder, an inconsequential amount of low-explosive albeit enough to seriously injure yourself. The consumer "M80" are even weaker. These are used to simulate real explosions by the military.
The smallest standardized military demolition charge contains ~110g of TNT, in a similar small cylindrical format. There are multiple orders of magnitude difference in power between an M80 and these demolition charges.
A "quarter stick of dynamite" isn't a standard thing. But if it was, it would probably come in around 50g of TNT equivalent.
Over the years they have found alternatives for and phased out most high-explosives used in fireworks. Many high-explosives will just deflagrate/burn but can spontaneously detonate with considerable power if the conditions are right, which makes them dangerous.
Or perhaps the safety improvements are offset by sellers now offering bigger fireworks (either because those are now actually safe and both buyers and sellers are more comfortable with them, or just because of a general hedonic improvement).
Or perhaps they are safer for their users, but worse for starting fires or interfering with low-flying aircraft.
Either way I would be interested in reading more about this, something more nuanced than "fireworks dangerous". At the least it's a counterpoint to what happened with illegal drugs which seem to have become more dangerous as a result of regulation and bans.
There is a parallel in military explosives research. For example, the US military is slowly moving toward “insensitive munitions” which use explosive chemistries that are nearly impossible to detonate accidentally due to fire or impact. This originated in nuclear weapons research but has spread to other weapon systems.
Fireworks are intrinsically dangerous in the hands of incompetence, ignorance, or stupidity. No amount of engineering can solve that problem unfortunately.
Primary = easy to activate, doesn't need an explosive initiator. High explosive = detonates rather than deflagrates.
And for bonus points, most flash powder is self-confining in very small quantities. Means a little pile of powder will detonate even if not enclosed.
Not unless you're purchasing on the black market or (illegally) manufacturing it yourself.† The professional stuff is substantially larger than anything sold on the consumer market.
† Which is surprisingly trivial to do BTW but please be extremely cautious and very thoroughly master the underlying theory if you decide to go that route.
I say this as somebody with a book on how to make them, but I've always been a bit too scared to try.
Along with the reminder from the safety coordinator that each firework was capable of completely talking your arm or leg off. The “consumer” grade fireworks aren’t capable of that, although they’re still dangerous.