Not so much that 'some employers are poo', more a case of 'most employers work within the legal framework that the government regulates'.
Pre-2012 it was 12 months service to get permanent employee recognition. Coupled with charging exorbitant fees for taking an employer to tribunal*, it has been very effective at letting employers shit all over short service staff for the past few years. As most of our employment protections come from the EU laws, coupled with the tories in at No 10, you can realistically expect employment protections to get much worse in the near to medium term.
*interestingly the Tribunal fees have recently been found to be illegal, and have been stopped. Great news but doesn't help the unknown number of people (including me) denied justice for daring to be poor.
EDITED: 20 Nov 2017 17:49 by KOSWIX