I've done keto, and I've done the restricted diets of paleo, and Adkins. To get into ketosis and stay there is very difficult.

That's not even remotely true. It's simply the state of your body using fat for energy (ketone bodies) as opposed to glucose. That happens whenever you limit carbohydrate intakes.

The other two diets don't even try to take you that far. You are still burning glucose, and your blood sugar will flucuate with how well you have limited your intake of the wrong foods.

Sure, but they are both fairly low carb diets. An atkins diet is explicitly such, as you're almost exclusively eating meat. Atkins diets will always result in a state of ketosis, and most applications of paleo limit carbs where you will be in and out of ketosis depending on exactly what you choose to eat.

I don't believe you ever actually get into ketosis on those diets.

I don't believe you understand what ketosis actually is. You should really check these resources out - they break down studies and actual science on the topics we're discussing:

https://www.youtube.com/watch?v=PKfR6bAXr-c

https://www.youtube.com/watch?v=5S6-v37nOtY

https://www.youtube.com/watch?v=KHaCKudtVi0

https://www.youtube.com/watch?v=LPxIssabhTc

https://www.youtube.com/watch?v=f_4Q9Iv7_Ao

https://www.youtube.com/watch?v=zcMBm-UVdII

https://www.youtube.com/watch?v=APZCfmgzoS0

https://www.youtube.com/watch?v=Dan8qtgQRi8

https://www.youtube.com/watch?v=dFT2IKmwyfg

https://www.youtube.com/watch?v=b7zWNabebxs

https://www.youtube.com/watch?v=isIw2AN_-XU

https://www.youtube.com/watch?v=hpOP_HKeazU

https://www.youtube.com/watch?v=xlfZvnV4v50

https://www.youtube.com/watch?v=-eefgRVi7Ko