If biologists could copy mice from other experiment to give them their own drugs and compare results, they would surely do this along with using their own mice.
The more ways to compare experiments, the more sure we will be about results.
I understand cleaning up code is a lot of work, so don't do it, just release it as it is. I know it will be ugly, will include obscenity, etc. If somebody need it, it will do the rest of work.
No. The more exactly you duplicate the original experiment, the more likely you duplicate any confounding issues. If someone observes something through a telescope, it's best to verify it through a different telescope somewhere else, to exclude the possibility of an optical quirk of the first telescope.
Some other people will run the same code on different data (maybe from simulation, or when checking their own theory). They will get some other results, or the same.
Some people will recreate experiment from scratch, and get code B and data B.
Some people will run code A on data B. Some people will run code B on data A.
Now we can't do that. The code is already written, it's waste to hide it, it's not like publishing code prohibit other people from writing their own code.
That's how you check for errors - by changing as little as possible and observing results.
In a sense, they actually do.
Saying you used a particular strain of mouse is like saying you used a particular algorithm on your data. Asking to use the exact individual mice used by another lab might not reveal an error such as mixed-up strains.
Besides, they're only inbred strains, not clones.
How does that come about? Patent shenanigans?
Pretty much anything 'lab grade' is going to be expensive. The lab I worked in ordered a lab grade laser for optogenetics experiments, and that cost something like $18k. Presumably that gets you a very precise, stable wavelength.
Also, a lot of the code may well be specific to the apparatus used, which may be unique to a lab, consisting of custom-built hardware.