There is 2 things to this, its cheaper to buy hardware like a raspberry pi or similar with 8gb of ram and use that to build the elevator. And it might genuinely easier to source the parts and future spare parts.
But as a developer I want to be snarky and say why does a elevator need 8GB, it should have 256MB and use 168 MB max where 100 MB is display graphics and music, 5 is the control system with 3 copies of the variable for redundancy and the rest is telemetry and a memory leak that eats 1MB every 2 weeks because someone is resizing the audio buffer for floor announcements everytime.
But its probably just a mini pc that's using 512Mb all in all running some linux distro. and the 8GB is just not being used.