Landlords themselves don't like to decide who has to be booted out from their premises, because then the offender can sue the landlord for unfair discrimination.
If you're having noise issues at 4am, most cities across North America generally have noise ordinances. Again, it's not the landlord that has to enforce such ordinances, but the police. I've lived in a low-rise 1b/1ba apartment building where an adjacent neighbour thought he was living in a "house", and had a home theatre system going up all night; the solution was to notify the police on multiple occasions, only after which the landlord would have the option to terminate the lease of the offenders, or face paying a fine to the city. (The landlord office themselves suggested that I either have to call the police, or, if I want, they could terminate my own lease without a penalty, since they couldn't act on their own in the situation.)
Your options at this point would be to call the police in regards to the noise issues at 4am, and discuss with the landlord the option of moving out without a penalty since the provisions of your lease are not honoured. Unfortunately, it's a bit unrealistic to expect and require that the every landlord will initiate any other action in the situation.