I can see where you're coming from, but I suppose it depends on your job and the standards expected. If you go into a job where being on time is important (and not necessarily just life or death ones) then being late is a problem. On an extremely rare occasion? Ok, these things happen but even semi-regularly there are jobs where it's not acceptable.
Ditto being off when you have a slight cold or feeling a bit tired or something. If you really are genuinely too sick to work, then take time off and stay off until you are well. But if this is happening frequently, then you do have to accept that this may become an issue for your employer.
I guess it's about balance.
I think many on MN would be annoyed if the school was opening 5-10 minutes late. Many people wouldn't be very understanding if their GP or hospital consultant arrived 15 minutes after they were supposed to have started their surgery or clinic (I have seen complaints on MN about GPs starting or running late). I know from my own experience if you say to patients that you will call at x time and you are even 10 minutes late many people will not be at all happy (even if you preface it with an apology and you have a good reason, such as dealing with an emergency or a previous consultation took longer than expected).
Generally, I think keeping clients waiting, not opening on time etc is something that shouldn't happen often in most workplaces. Obviously, things like hospital and so on where you are dealing with an unpredictable work load this can be difficult (but that is different from not bothering to be in on time).
We have an issue at work where one worker will quite often leave 10 minutes early if her last slot is not filled (and another group of workers can't ever leave early, even if no-one is there t be seen as they work in reception and phones need to be answered and so on until end of the day). The person who is leaving could be required to help in an emergency so not being there for 10 minutes may seem insignificant but it could have an impact on everyone. Also, it is really irritating for the group of staff within the team who can never just leave 10 minutes early. This staff member is also one who gets very irate if anyone ever asks her to work through even 5 minutes of her break (even if she gets 5 minutes on the other end of it) and is very inflexible. She does her own duties to a reasonable level, though never really put herself out for anyone and isa bit lazy. She does, however, frequently want to move her hours around but people's willingness to find ways to work around this has rapidly diminished due to her general attitude. It is leading to tension with the team and now rule changes have had to be put in place that impact everyone as we can't be seen to make rules just for her. I'm sure if you asked her, she'd see it differently.