As a project manager in a non union shop, I think the workers are exactly the same.
Sure they can because historically, before unions, they came out really well in those negotiations. Usually they were given the added benefit of having indefinite unpaid vacation.
Experiences will vary.
My situation....
I've worked for some large employers, U of Mich, Northrup, GMC, Koppers Co,
& dealt with both union & non-union types. Particularly with U of Mich & GMC,
the unions were all about doing little work.
I've hired both union & non-union workers (although no union in my businesses)
as employees & for contractors. The noticeable thing about the union workers
was that they were slow.
The above experience ranged from 1973 thru 2007
The different mindsets.....
Those in a non-union contracting environment think in terms
of a price for a job, & work efficiently so as to fit in more jobs.
Union hall workers have an hourly mentality....the more hours
you take, the more money you make.
And then there's how they treat tools....
A contractor breaks a tool....he knows he must buy a new one.
A union guy breaks a tool...the employer will replace it while
he's on a break.