I disagree. Rope Trick is not a concentration spell. A simple minor illusion prior to the rope trick can fairly easily prevent foes from knowing you're in a rope trick.
Disagree. As Treantmonk himself points out, there are plenty of tools usable to be able to find a rope trick, if you suspect one is around:
1. Truesight (largely restricted to higher level/CR opponents; this also defeats illusions)
2. See Invisibility (the entrance is "invisible", so the entrance can be identified easily by someone using this spell; it also lasts an hour)
Note: the remaining items/spells depend on the entrance to the Rope Trick being an 'object' by 5e rules, which is not much of a stretch, since the usage of 'object' in the rules is basically synonymous with 'not a creature'.
3. Detect Magic + Faerie Fire (as 2 -- Faerie Fire notes that "[e]ach object in a 20-foot cube within range is outlined in...light" -- but the Detect Magic spell is required to identify the area in which to cast the Faerie Fire spell. Note that Faerie Fire has a range of 60 feet.)
4. Figurine of Wondrous Power - Onyx Dog ("...has darkvision out to a range of 60 feet and can see invisible creatures and objects within that range.")
5. Robe of Eyes ("You can see invisible creatures and objects...out to a range of 120 feet.")
And these are just the ones I can easily find in the SRD -- I'm sure there are other potential counter-measures available. Just end an adventure with a team of NPC assassins hiding in a Rope Trick somewhere in your PCs' stronghold, and I'm sure they'll come up with more options by the next session.
Frankly, I'm not sure if I'd have the monsters dispel the Rope Trick before the duration (and the short rest) ends, or if I'd rather surround it with a Wall of Force that contains a couple of high CR swarms.
And if you do the rope trick out of sight of foes around a corner, you might come back into hostile territory but it's not an ambush situation either.
If you're just talking about 'the wilderness', then sure, nobody's going to necessarily be doing guard sweeps and the like through the woods. But an evil temple, monster lair, or similar location? You've got some pretty chill monsters if they become aware that their home/base/etc. has been invaded by adventurers but decide to just passively sit around until the adventurers show up to murder them. There are always going to be exceptions (Castle Ravenloft, for example), but most places are probably not going to sit back and relax while a party of murderous PCs rests up in a side corridor, especially not if the resources required to find that party are fairly minimal.
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Pauper