The article Will QR Codes Make a Comeback in 2019? says "Twice as many respondents in Europe and North America scanned a QR code in the past month compared to Q3 of 2015." But regardless of such optimistic forecasts, I would still go back to the basics.
I have added QR codes that point to websites, but not since 2012 and not on printed business cards. I probably would not do so unless needed as an accessibility features, such as low visibility. For example, is card's target audience folks in night clubs? See Using QR Codes to Make Presentation Materials More Accessible. Designing for a US audience, nowadays, I might add a QR code to trigger a highly valued experience: a special experience online or sequence of events on the local device. And I would make sure that a prompt or call to action encouraged the user to engage.
The Scan and Shake: A Lesson in Technology Adoption from China’s WeChat is a bit old, but has sound discussion points about adopting technology. They call out three conditions for adding an interaction element: Usefulness, Ease of use, and Discoverability. Given those condition, in discussing QR codes for website landing, I would discuss with the client:
- Usefulness: In the US, the user would need to know what feature the
QR code provides before bothering. How can we incorporate the QR code
to make it clear that it can be used instead of typing in the website
- Ease of use: Let's compare QR scanning & triggering URL to
typing in the URL. Which experience is easier?
- Discoverability: A QR code is definitely discoverable on a business card,
but see "Usefulness" -- the feature, itself, needs to be discoverable.
Otherwise, it's just visual clutter.
I hope going through this sort of thought-experiment with your client results in either dropping the QR code feature, or transforming it into an exceptional experience for their users.