We cancelled a gig on the day earlier in the year as my dad became ill and was taken to Hull A&E - he's 93. We do specific arrangements so a dep would have been pretty difficult. The pub were relaxed and have rebooked us.
This would all have been trickier had we been a function band or if we had been regarded as more of a "name" band, but then in those cases, formal contracts would probably have been in place per mrtcat's post.