Earlier quoted context omitted.
Striking should be ubiquitous; employees should be in unions by default with no voting required.
Why would you abridge my freedom of association by forcing me to be part of a group I have no desire to join?
This model does not put you in a group anymore than being an American citizen puts you in a group by giving you the right to vote on things. In my version it is like how you get to be in a political party if you want to and not be in one if you don't, but you get to vote either way. The right to have some say against your manager's power in your life (short of quitting, that is) should be unassailable.
The fact that quitting is "all or nothing", and often not an option to people because the cost of finding a new job is high and often prohibitive to specifically the people who are most disenfranchised, makes it a poor and almost useless way to exercise power. Unions allow, in principal, for there to be intermediate pressures between "quitting" and "asking nicely".