Fully verifiable work history for 3 years ask by Employers / Trucking Companys?

Fully verifiable work history for 3 years. Can anybody clue me in on this.
Why. History etc.
What not to say or do.
How not to screw yourself etc.
??????????????????????????????

Thanks in Advance

 

Okay. as an example a guy has 3 years proof but for the last 7 months hasn't worked and can't prove wether he has or not.... something like that or ??

 

So the guy still filed his tax returns and had proof of his last time he was employed ( equal to 3 years )

also wondering why EXACTLY this is the way it is ?????
Why do they do this.
IM just wondering?

Thanks in adavance

 

who did he go with?

I happen to know a guy whose having a problem because he's waiting for paper work from IRS
and made mistake of saying he worked this year even though he didn't because he didn't want to
seem lazy
and now the company is hassling him and said they can't hire him at this time even though he said look i didn't really "work" this year but did odd jobs for cash etc.
anyway other than that has a good record like me ,,,,, makes ME nervous to go looking for a company when I'm ready in a month. anyways

 

Oh yea so WHY is this 3 year thing , a Thing???