I think that principle (ignorantia juris non excusat) only applies when you have knowledge of the facts that your own act would violate the law. It doesn’t really apply to aiding and abetting when there is no knowledge of the fact that your taxi is being used to transport a person who will receive an illegal abortion.
Now, dropping a woman off at a dedicated abortion clinic - that may be grounds for liability. The woman tells you she is on the way to get an abortion, liability. The woman asks you to drop her off at some intersection that happens to be near a women’s health clinic among other businesses? Probably okay.
The term is mens rea. It essentially means you have to have intended to commit an act that you knew was a crime.
The opposite term is strict liability. This means you’re guilty of committing a crime even if you were unaware that what you were doing was illegal.
There are also terms like knowing, malicious, negligent, reckless, and specific intent which have legal meanings about the connection between a person’s state of mind and the illegal actions they committed.
regardless of whether the person knew or should have known that the abortion would be performed
This clearly says that if you drive a woman to a place where she is having an abortion, you are legally liable. Even if you are unaware that she was going to there for that purpose.
knowingly engages in conduct that aids or abets
the performance or inducement of an abortion, including paying for
or reimbursing the costs of an abortion through insurance or
otherwise, if the abortion is performed or induced in violation of
this subchapter, regardless of whether the person knew or should
have known that the abortion would be performed or induced in
violation of this subchapter;
Not knowing there would be an abortion at all is still a defense.
In criminal law, that’s not what mens rea means, and that’s not what strict liability means, but it doesn’t really matter here because this is not a criminal law.
I think the “knowingly” part of the law can be read more than one way, so it will depend on how Texas courts construe the law. That will likely depend in part on legislative history. So what did the legislators say about whether Uber drivers could be sued? Was it their intention to include them or not? Under what circumstances?
My guess, reading the whole statute as quoted earlier, is that the intention was to create liability for anyone knowingly assisting with an abortion, if it turns out that the abortion violated the law, and the person providing assistance did not have to know that the abortion would violate the law (that last part is expressly stated).