It's not, at least not everywhere. I have crossed the border between France and Switzerland more than a dozen times in the last few months and, on most occasions, I haven't noticed any police presence. It's more common to see French police/gendarmerie/customs but they seldom check passports, mostly look at people and wave them through. On one occasion, taking a train from Geneva station, the French police did check everybody's ID (looking at passport's ID page but not at any visa people might require).
That's not to say check are not frequent at some border crossing points (establishing that would require much more than the kind of anecdotal experience I can provide) and it's entirely possible that checks would be more common on the border with Italy, on trains (I have taken a few but mostly cross the border by car), or on the motorway. For some reason, I also have the feeling that the border with Germany was always more intensely policed (all the way back to pre-Schengen times when checks on the Swiss-French border were already far from systematic).
Back when checks on long-distance trains were common (and I took such trains regularly), I always thought that there was some profiling going on, not everybody had their documents checked, or not as intensively, and it didn't feel random at all (although it's again something that's difficult to establish based only on casual observations).
Finally, one problem specific to Switzerland (compared to other Schengen internal borders) is that it's difficult to draw the line between a customs and an immigration check. I remember that the EU Commission initially indicated they would be very sensitive to that but the fact is that it's perfectly legal for Swiss law enforcement to be present on the border (for customs purposes) and if they ask questions and only occasionally check IDs, it's difficult to establish that this amounts to a border check (technically, there are two agencies in charge of border surveillance… but both are part of the Federal Customs Administration and, in principle, competent to handle customs matters or, indeed, unrelated offenses they might notice in the course of their duty, like drunk driving).