Sorry to say, but:
As a landlord of a residential property, you are considered as in a business. As such, you should know ALL the laws pertaining to that business - RTA 2004, Housing Standards for rented accommodation, Tax laws and PRTB requirements to mention a few. Ignorance of the law is no excuse.
Being a landlord is NOT the easy option that many people (especially tenants) believe it is. As a landlord you are renting out a property valued in most cases well over 100,000 euros.
If you called a plumber and he didn't know his job, you would be upset. If you went to the dentist who didn't know his job, you would be upset. If you went to a solicitor who gave you incorrect advice, you would be very upset.
If then, as a person in business you do not know the laws pertaining to that business should you not be penalized?