There are certainly mechanical and electrical challenges to building really reliable robotic systems with 98%+ uptime 24/7 in a logistics or manufacturing setting, but it's mostly applying good best practices and design for those engineering disciplines. Sensors and actuators can still be a challenge in some settings for sure. I think many of the really difficult (and fun) problems today are in the software. Even traditional automation shops used to basic PLC programming are starting to recruit and grow software engineering teams.