It’s a sad fact of life in Silicon Valley that the people who work the hardest are paid the least — and, for the most part, are completely invisible.

Invisible, that is, until they go on strike and somehow inconvenience the lords of the economy: the techies, entrepreneurs, financiers, and bloggers who generate the most wealth and fancy themselves the center of the Bay Area’s universe.

That’s what happened a few years ago when janitors went on strike, and suddenly the people who worked in downtown high rises found that wastebaskets don’t automatically empty themselves overnight.

It happened when hotel workers went on strike and conference-goers and tourists were terribly inconvenienced by the crowds of people below, shouting and chanting and waving signs about the need for fair pay, medical benefits, and respect.

It happened two years ago when the disorganized cry of rebellion known as the Occupy Movement started filling the streets with almost daily marches, chanting crowds, and drumming. (God, the drumming!) The protests got so bad that some people could’t get into the bank branch of their choice for half a day or so. Once, I was even stuck in VentureBeat’s office building for half an hour while someone on the P.A. advised us to “shelter in place” because a protest was happening downstairs. The horror!

Now, transit workers who make the trains run (sort of) on time at BART, the Bay Area’s biggest municipal train system, have gone on strike — for the second time in several months.

During the brief summer strike, we heard the kind of tut-tutting that only a super-entitled San Franciscan could muster. Fortunately, this time around the howls of outrage are more muted, but there’s still a lot of complaining.

To which I say: Suck it up, San Francisco.

The strike has shut down a system that carries, depending on which estimates you believe, between 200,000 and 400,000 commuters every day. Yes, it’s damn inconvenient. Two of the people who work at VentureBeat live in the East Bay, and they’re staying at home, because there’s no practical alternative to BART — driving in to San Francisco would just take too long.

For tech workers, staying at home is actually an option, and a pretty good one at that. (Unless you work for Yahoo, presumably.) Most of the entitled young folks who earn six-figure salaries a year or two out of college just because they know a little Python are able to be just as productive at home, or in some coffee shop, as they are at the office. They’re probably even more productive, because they aren’t wasting time at the company kitchen, the company ping pong table, or the company rope swing.

The ones who are truly inconvenienced are those who can’t get jobs with flex-time, work-at-home options, or any kind of paid time off at all. The jobs where, if you don’t work a day, you don’t get paid for that day. The people who clean office spaces at night, vacuum and mop apartments during the day, drive cabs, work in restaurants, or pull double ristrettos at trendy coffee shops.

What’s more, it took a tragedy to drive home the fact that the BART strike is not about a bunch of entitled people demanding more. Well, BART workers are demanding more — but, for all the system’s dysfunction, most of them are not what you’d call “entitled.” They’re hard-working people who put in long hours to move thousands of people safely from point A to point B. And for some of those people, their jobs are in fact a matter of life and death.

Two BART workers were hit by a train during a maintenance operation on Saturday, just one day into the strike, and were killed. The employees were inspecting track when they were hit by an automated train. It’s not clear if the strike played a role in the deaths, but either way, it’s a horrible thing.

The accident is also a tragic illustration of the fact that, underneath all the rhetoric about how “software is eating the world” and “hardware is dead” someone still has to make the trains run — and trains are big, heavy machines that can hurt you.

There are machines like that behind the surface of every web site, every software-as-a-service startup, every so-called “cloud.” There are generators and engines and construction equipment and roads. There are mechanics and engineers and pipefitters and janitors and housecleaners. You can pretend that the physical world doesn’t exist, but someone is still working there, cleaning up your messes and making sure your lights stay on.

Think about that while you sit in your favorite coffee shop, working on a business plan for how to disrupt public transportation.