Edit: https://casa.sapo.pt/ for a look at the real estate market. "para venda" is for sale, "para alugar/aluguer" is for rent.
42000€ per year gross salary lands you in the 28.5% income tax.
A yearly gross salary of 42000€ is about +/- 1800€ salary/month.
The distinction is largely a technicality, all the more because both parts of the SS contribution are paid by the employer directly to the state, but it does have one effect: because the 20% don't show up in the salary receipt, most portuguese people are, like you, blissfully unaware of what the real tax rate on their salaries is.
I've heard that falacy time and time again: "Oh, if I didn't have to pay so much taxes for each worker I could pay higher salaries."
What would happen if those taxes were lowered is for economists to speculate, I'm not one (even then, as the joke goes, put a question to two economists, get three different opinions)
[0] This conversation made go check the exact values, you can find them here: http://www.economias.pt/contribuicoes-para-a-seguranca-socia...