Anti Siphon S Trap

Was looking for decorative angle stops and came across a anti-siphon S trap. Contraption looks like a S trap with a Bottle Trap in the mix.
Are these code legal in this day and age.

See pic for review.
The white PVC ties into a larger vent stack above.
On the right hand corner, about 4 feet away is where the drain is a kitchen sink.
It's been years...sink has never siphoned yet.

There is no trap there at all. That's just a sanitary tee on it's back (illegal) and an elbow into the other end.

People have been inventing "siphon proof S traps" for years. Mostly they consist of a chamber to hold a mass of water which the siphon cannot pull the whole amount out, so some "drops back" to maintain a modicum of a seal. The laws of physics make it "impossible" to create an "S" trap which does not siphon. While they may work, and you have absolutely NO IDEA whether the drain has siphoned during those years, they usually violate some other "standard" for a legal trap, such as "no internal baffles", "not self scouring", "smooth waterway", etc. They can make and sell anything they want to. It is up to the user/installer, (and the inspector), to determine whether it is a prohibited fitting or not. You have a photo of a drum trap. It is just a smaller version than the ones used under bathtubs, and would NEVER pass inspection.

The pic was to show under the SINK DWV.
The PVC is a vent. It makes a 90 - on the right going right underneath a cabinet to a S Trap

the Anti Siphon looks like this

I must be either blind or missing something because I don't see a trap of any kind in the first picture. The last picture is a drum trap and half an S trap bend. BTW, drum traps will not siphon but they will collect all kinds of crud and fill up

THAT drum trap WILL siphon, but it just has enough water that some will remain to give a bit of a seal.