Well let's get real for a second here.

Suppose you rely on Public Transit to get around.

You get a job, you check the bus schedule...there's a bus that drops you off right outside of work at 8:50.

That's pretty reasonable imho.

However, fairly regularly the bus is going to be 5 minutes late...this may cause you to be exactly on time..maybe a minute late.

Also fairly regularly the bus will be 20 minutes late...causing you to be about 10 minutes late.

Rarely it will be even more late, but not very often...probably about as often as a commuter gets stuck due to an accident or something.

Is it really a big deal to be 10 minutes late sometimes for an unavoidable reason?

I could see if you had to relieve someone, but again..let's get real. Most HN readers probably don't HAVE to be at their work exactly on time.

Buses generally run about once every 1.25 hours...even upt to every 2 hours.

Is it really fair to ask someone to be at work 1.5+ hours early every day just so they are not occasionally 10 minutes late?

The problem is with PT, you have basically 0 control over things. If you are driving a car, you can listen to traffic reports, avoid congestion, drive faster, take shortcuts. With PT you are completely stuck.

This is not a contrived example, this is based on what I have seen with Public Transportation and people using it to get to work. Unless you live downtown or in a city with excellent PT, you can find yourself in this dilemma.

It's easy to write it off as avoidable, but it seems silly in my book to advocate going through a huge hassle just to avoid being a few minutes late.

Obviously if it is critical that you are there at a certain time, that's a different story. If I'm a surgeon who needs to be on call 24/7...taking the bus is not going to cut it.

I'm also not saying we should give carte blanc to people to show up whenever they want...

However it's something that really depends on a lot of things.

There are a lot of things that can cause a person to be late, are most of them preventable and avoidable? Yes, but the effort may not be proportional to the benefit,

I honestly think these days showing up exactly on time is disproportionately valued.

It's definitely a factor, but it's one of many and if someone is a little late but good elsewhere I don't think it's a big deal.

Very good engineering analysis explaining the tradeoffs and that no system is perfect.

The problem is that I value my own time more than I value other people's time.

Then I suspect that you would not fit into the "professional" category as defined by the OP. (That's not to suggest that the OP's definition of the word is the only appropriate one).

So do I but,

1. I carry a Kindle with me. I read a lot and I can do it as well waiting in a office/lounge/Airport as at my bed.

2. I don't value my time more than collective time of four people waiting for me to start a meeting/meetup/lunch.

This reminds me of an idea I had for a product: place value on your and your colleagues time by creating a market for it. The market runs in the calendaring application - you are allocated a certain amount of everyone's time to take for meetings. If you want or need more than your allocation, you have to trade for it. That way you are forced to invite only the people you really need, it quickly becomes obvious whose time is most important, the overall amount of time spent in meetings is limited, and people become cognizant of the "value" of others' time. It could be built as an outlook plugin, even.

no link handy, but a similar thing was tried with email before. You had to offer points for someone to read your mail, and readers would natutally read the highest-paying emails first. The results sounded cool, similar to what you were predicting-- everyone got more conservative with others' email-redaing time. With the email version, you "traded points" by reading (or replying? I forget) your mail.

I'd love to try your calendar version!