Ouch ~ that surely does suck when it comes in threes like that ... but I do believe that everything happens for a reason in life and we just need to be detetive to figure it out ... my hope is bigger and better clients are around the corner for you!
And to answer your thread title question no not all clients are that unreliable ... but since they do not where a sign that says 'I just might screw you over if it suits me' I always do things to protect my income as best I can for the inevitable possibility of clients leaving unexpectedly!
Always get paid in advance of service .... they are less likely to bolt when laid off or whatever if they have already budgeted to have paid you for two weeks of care so they might as well 'finish out the two weeks' giving you more time to find a replacement!
It is one thing to 'ask' people to give you X amount of notice but if you truly want/need proper notice of termination ~ make sure you keep a deposit equal to the amount of notice you want! A deposit that is clearly defined as non refundable and can only be applied to the last weeks of care provide the proper notice has been given by the client or provider. If for some reason you want a client GONE but do not have legal grounds to terminate with 'cause' you can always choose to 'waive' that rule and refund the deposit verses giving notice yourself and having to keep serving them but at least than the ball is your court financially! Most providers require a two week or a month notice and therefore equal amount of security deposit!
Sending you some better days ahead vibes!