development accounts are for development, liek tstdrv123456 (test drive)

I thought tstdrv accounts were SDN accounts? When I had development accounts at a previous job they had regular numeric account numbers. At one point (or maybe still) they were giving three with each sandbox. However they come without any data and can't be refreshed from another environment.

you are probably correct, I have not personally used any other kinda side from those so I assumed tstdrv == development

development has it's own account type - with a regular 7 digit account code!

I think in scripts development accounts identify as production

they do, after checking the behaviour of bundling they did follow this idea rather than sandbox!