There's lots of options, but they come with differencing costs, effectiveness, reliability, compatibility, and ability to handle lots of traffic. It's a spectrum all the way from fully automated operation (like you see in some overseas metros), down to 'be ready to stop if you see something' (goods yards).

Auckland has ETCS Level 1, which provides cab signaling and speed limit info, and stops trains before they can SPAD or over speed. But the equipment is only fitted to the EMUs, not locos. The train needs to know all its braking characteristics and the track slopes etc., or you have lots of false activations.

Wellington has conventional signaling, with tripcocks at critical signals. These raise a lever on the trackside when the signal is at danger, which trips a valve applying the brakes if a train passes it. Again, only on EMUs. A complete redo of the signaling interlocking, along with the installation of ETCS L1 (or similar?) and wrong line running is expected in Wellington in the next decade

Main trunk lines are mostly conventionally signaled, with limited cab signaling in the central NIMT (installed with the 80s electrification). Branch lines are often Track Warrant Control, meaning you radio the signaller to get permission for each section of line.

I’m novice too but have worked on rail as a surveyor (slip monitoring etc…) They have an app that lets them know lots of things so it’s kind of automated and shows info such as train positions direction etc …

The automation methods are around recovery from the SPAD, for example by automatically applying the brakes, alerting the train operator, stopping other trains in the section, etc (specifics vary around the world, and I don't know what specific actions apply here in NZ)

But those mitigations don't negate the fact that a SPAD occurred, and the driver doesn't get a free pass just because automation stopped their train.

Even if the train is slowing to a stop, but proceeds a few metres into a red section of track, that's still a SPAD, and is treated as just as serious an incident, as if the train had carried on at speed.