I don't think we need to tell parents every little thing that occurs but IMO minor hitting/pushing/crying which is consistent needs to be brought to the parents attention so they are aware that it is becoming a problem and that you are working on it. Also as a parent myself I would hate to hear after an extended period of time that there have been issues and suddenly just be told once things chad escalated. Just let them know without blowing it out of proportion that this is what is going on and this is what you are doing to deal with it. As far as the getting progressively worse at listening, which is still normal for the age group depending on the child, when it gets to the point that he is running off, it becomes a safety issue and must be taken seriously by the parents regardless of how laid back they are. They need to get on board and be held accountable for reinforcing what you are doing at daycare to modify his behaviours.
I would be very clear to parents on what you need from them to reinforce what you are doing and then explicitly tell them that you will set a specific timeframe to discuss and review how this is working, and do this right from the start by saying let's talk in 6 weeks to discuss progress. If you see things are not improving and are getting worse and you have a strong inclination that the Parents are not being consistent and working with you, then I'd consider terminating only because these behaviours should be easy enough to rectify given time, but if the parents don't get on board then you are fighting a losing battle.
I have no problem working with difficult children, it's up to us to teach them and help them, but without full commitment from the parents, your efforts will not be enough and things will likely escalate.