They did not ...what? treat you as a legitimate independant contractor or withhold and file for you?
I doubt seriously all these companies are in violation of the law.
I doubt it as well.
If you received a W2 from them, then they computed your gross from a timesheet you submitted, paid you the net after taxes and they withheld and filed for you, treating you as an employee (probably hourly and without benefits).
Else, if you received a 1099 from them, then they treated you as an unincorporated independent contractor (DBA, sole-proprieter, LLC), paid your invoices, withheld nothing and reported only a copy of the 1099, and you were required to withhold and report your self-employed FICA contributions.
End if, you received neither (and they withheld nothing), then they treated you as an independent contractor, paid your invoices and assumed you were incorporated (otherwise a 1099 is required) and further assumed you withheld and reported your own employer plus employee FICA contributions.
There are no other lawful scenarios. One way or another (lawfully) either the entity who pays an employee, or the independent contractor who pays himself from receivables, reports and withholds FICA, from which reports the labor stats are derived.
Did you submit timesheets only, or invoice as "LS Consulting" or "LS Consulting, Inc."