In certain work environments it's pretty common. It also depends on how well you guard your boundaries.
Just because your single and don't have children, a lot of people with children like to assume your private time has NO VALUE. They feel like you are not in a position to refuse working till late in the evening.
They act like having children is something that was out of their control. Of course I realize how accidental pregnancies CAN happen. I've had my share of pregnancy scares too! But don't start guilt-tripping me when you have to face the consequences of you not wrapping it up when you were desparately effin that hideous ***** night-after-night.
Corporate brain-drain
At bigger (500+ employees) companies, the HR departments consist of solely female employees. When times get rough and the company has to lay off an X amount of employees on the workfloor, guess who goes first? Unmarried, childless men. By default.
Why? Because those women would feel bad
for laying off someone with a child. Forget about rational, business-like decision making when there's women in charge.
Personal example:
Four years ago I worked at a company with about 30,000 employees. At a certain point they had to lay off around 5,000 employees, to prevent bankruptcy. As a single guy, I was immediately put on the list of people to be dismissed.
Quite frankly, the previous manager I worked with for two years heard about it and thought they were insane for firing one of the few guys who actually knew his job inside-out and did it WELL. He got me transferred to another department.
Bottomline:
As a single guy you ALWAYS have to deliver on the job. No excuses.
