How can I tell if a message is a scam?

It's a scam.

I got a message just like this one yesterday. The only difference was the date. (In both cases, "today", the better to panic you and get you to give your financial information and money to the criminals.)

I also received the exact same message a while ago. This is a prevalent scam attempt. Do not interact with it.

This article also has some good information: Recognize and avoid social engineering schemes including phishing messages, phony support calls, and other scams - Apple Support

Yes, it's a scam

Yes!

https://www.topsidefcu.org/blog/fasttrak-toll-texting-scam

NewsWeek – Drivers Hit With FasTrak Toll Scam Texts—Here's What to Watch Out For

ABC 7 News – FasTrak warning drivers of new texting scam: Here's what to know

Here's a larger screenshot of the fraud warning on what seems to be the real toll site:

Hello~ Yes…it’s a very effective scam right now in fact. I treat everything as a scam right now at least until I can prove otherwise. Report it then remove it and move along. Don’t interact with that at all and good that you asked. Take care.

~Katana-San~