There's a lot of variance worldwide in turnout in referenda. If a referendum is phrased in a way that people see it as vital to their day-to-day life, they can easily imagine what a “yes” vote means to them and their families and what a “no” vote means. They can feel it, right? That's the time when they turn out.
If it seems like an arcane and abstract thing that really isn't connected to their life, perhaps something that just the elites are arguing about, that's when they stay away. Even if they go to the polls to vote for another candidate, there's this idea of drop-off, where if a referendum is just too confusing or too abstract, people just wash their hands of it. That's the main variation.
The other thing that I'll say is that, when that happens, the people who are more likely not to turn out tend to be people who are are lower on the socio-economic scale. If you're worried about people who have less education or less income being part of this process, then if you have a situation where the referendum is confusing and the interest groups aren't telling people what's going on, the folks who are most likely not to participate would be those lower on the SES and of lower education.