The point is that even showing up costs time and possibly travel expenses. Court proceedings are slow, so without a lawyer, you'll spend days of your time in court fighting the case.

It's possible to defend yourself without a lawyer. People have done it successfully. However, to be successful, you have to spend a lot of time learning, understanding and using the law to your advantage, and it's usually not worth it. Even lawyers will hire other lawyers to defend them, if they're defendants in a case outside their area of speciality.

There's a pervasive attitude that representing yourself without a lawyer lowers your chance of winning, though there are no hard statistics either way.

If you don't show up at all, you'll almost always lose. In many cases, if you fail to show up, the judge is required to rule in favor of the only party that showed up. Even if that wasn't the case, if the judge is only listening to one side of an argument, they're likely to agree with that side.