[Nebullis]

...people expect perfect randomness, where randomness in actuality is constrained in some fashion?

The constraints just mean limitations of the area over which an event is unpredictable ("perfectly random"). Let me give you an example. Aflotoxins cause DNA mutations by binding to parts of guanine residues resulting in a G to T transversion. The toxin is very biased in this affinity, because it only binds to G and not to other nucleotides. At the same time, the toxin has no affinity for one available G over another G. It is constrained by chemistry, not by a directed or goal-oriented process, and, as such, it is still unpredictable within those constraints.

[unspun]

The constraints just mean limitations of the area over which an event is unpredictable ("perfectly random"). Let me give you an example. Aflotoxins cause DNA mutations by binding to parts of guanine residues resulting in a G to T transversion. The toxin is very biased in this affinity, because it only binds to G and not to other nucleotides. At the same time, the toxin has no affinity for one available G over another G. It is constrained by chemistry, not by a directed or goal-oriented process, and, as such, it is still unpredictable within those constraints.

And this proves what?

[Heartlander]

When speaking of DNA you are dealing with an information message that is read, translated, and put to use. Bottom line here is that in cryptography (or a CAD database to a CNC), a message must serve a purpose or it cannot be used. What good is an error in a message or DNA (due to chemical mutagens, bad signal, or design) that causes the information to be of no use? Misinformation that causes death or cancer would be seen as toxic as well. If you want to associate evolution with random death or something of no use, that is fine though…

I guess there is no constraint to the randomness of information if there is no constraint to usefulness of information.

But that is what you meant when you stated in regard to DNA:

The constraints just mean limitations of the area over which an event is unpredictable ("perfectly random").