You can be pressured still with paper voting: They can just ask you to take a picture of your voting card with your mobile phone. It's illegal but no one will notice because, guess what, you're in a private voting booth that no one should be able to see into.

There are ways to avoid being coerced when enabling online vote: have an online vote for a week, then a few days after the online vote ends, have one day of paper voting. If you were coerced during the online vote, you can still go to the paper vote later, at which point your online vote will be overwritten by the paper vote[0]. This is still not fool proof (i.e. one can force people not to go to the paper vote after coercing their online vote) but as explained above, neither is normal voting.