I'm a millennial who has watched the complete failure of my generation to realize the promise of those Obama 'Hope' posters.
"Everyone don't do X" runs into problems when there are clear incentives to do X. Like, say, grades which eventually will be used to determine who gets to graduate, who gets into which schools, who ultimately gets easier access to higher paying jobs. And simple convenience is an incentive in itself - if doing X saves time, it will be the default.
This same dynamic is why we still have a climate crisis, even though everyone has known about the problem for thirty years.
"Everyone just do Y" is what we call a collective action problem. When there are clear incentives to defect, it is also a free rider problem.
"Everyone don't do X" runs into problems when there are clear incentives to do X. Like, say, grades which eventually will be used to determine who gets to graduate, who gets into which schools, who ultimately gets easier access to higher paying jobs. And simple convenience is an incentive in itself - if doing X saves time, it will be the default.
This same dynamic is why we still have a climate crisis, even though everyone has known about the problem for thirty years.
"Everyone just do Y" is what we call a collective action problem. When there are clear incentives to defect, it is also a free rider problem.