Among other reasons, the high pressure of Venus and the gas giants atmospheres are often stated as one of the major problems for an unmanned lander. They say the pressure will "crush" the probe. Why is high pressure a problem? Of course you can not have a confined space of gas or vacuum , or foam containing small bubbles of air on-board, but that should be easy to avoid.
edit: Just to clarify, I am totally aware of the terrible environment of Venus, I just wonder about why high pressure in general is a problem.