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Another point on efficiency would be added if the ability to save notes and re-use them were added. This would be simple if the "Leave a note" line had a drop-down arrow, with previous note titles there. This would also require dealing with the idea of "titles" for notes; for simplicity's sake the current note interface has only one text box. This single-text box approach improves efficiency in the short run (the first time a note is written) but avoids the ability to re-use notes, which would be a boon to longer-term efficiency.
Having all the possible enabling icons in the same place on the "Leave a Note" page as essentially check-boxes (with highlighting instead of checks) makes changing these options pretty efficient.
Safety
The ability to edit a note would be one possible safety feature to add to this design. We could enable this by allowing the user to edit the note visible from the home page. The interaction between this possible feature and the idea of saving notes might have to be carefully managed. The app enables better safety than the "naive approach" to laundry because it enables the possibility of contacting the owner of a load of laundry to inquire about instructions.
Other safety issues with this app include the irreversibility of some decisions. For example, if a user clicks "Done" by mistake from the page where one can view a note left by another user, then in the current version it seems impossible to reverse this decision. The app should reverse decisions and return to previous pages when the Android "back" button (bottom left) is pressed.