Even if we can guarantee the votes are submitted and counted accurately, it's impossible to tell if my boss was standing behind me telling me what to vote (or lose my job).
At a polling station they prevent coercion by enforcing secrecy. One person in a voting booth at a time, no cameras in the voting booth, etc. If you can't prove you voted either way, you're free to lie about how you voted.
Or, much more likely and hard to change, a domineering family member making sure everyone votes the same way.
Then you just say you already voted and lie who you voted for. What will they do, confiscate your phone? (assuming phone voting). There are so many "outs" to the coercion scenario that it seems implausible that it would ever occur on any significant scale. What scenario can you think of where coercion would be a real issue?
Forget about intimidation and consider bribery. Instead of a domineering boss threatening termination imagine a man with a laptop and a roll of $20 bills.
I don't even see an easy workaround, either... Hrm...