Does this include statements made under duress?

Yes. There are two parts to this: parties in a trial are free to present any evidence to the court, no matter how it was obtained.

However, the court alone decides the value of the evidence presented, and thus the weight it places in such evidence.

Obviously statements from people suspected to be coerced in some way is not considered high-value evidence.

I am shocked. This is an awful policy!

Most countries have similar laws. The US is fairly unique in its strong laws about inadmissible evidence. The argument for those policies is that it stops people being let go on a technicality due to someone signing the wrong form or whatever.

However just because evidence is admissible doesn't mean it has to be taken into consideration. Often the court will decide that certain evidence won't be taken into consideration due to how it was obtained. This is an entirely separate decision than whether or not it should be admissible.