Everyone has access

Finishing up a watch thru, and yes, I know this is me being nit picky. It just seems way to easy for anyone, starfleet or not, to gain access to any system they want and lock out the Capt. and any other crew member regardless of security clearance. I understand that they use this to add suspense and tension, but c'mon man. Some alien they've never encountered can lock them out of engineering and block transport whe they steal the warp core pr whatever, and Janeways overrides are absolutely useless!? And something that probably drives mecrazy more than anything else, is the evasive patterns. Then just cut to a shot of Voyage going straight as the enemy ship fires all willy nilly on them. Direct hits every time. Alpha this, gamma that. It's all the same. This is all more of a vent than anything else. Still love the show.