Strange - people have complained about how easy it is to hit things due to the changes Larian has implemented in 5e (lower AC in some cases, more magic items, easy advantage).
1) Gaining advantage is easy - in your proposed scenario, if you shift your character behind someone to "backstab" them, you immediately gain 20%+ accuracy as implemented in BG3
2) Tons of magic items in BG3 compared to table-top. You can even get a +2 weapon in EA which is HUGE in 5e D&D
Given those 2 factors, you should be seeing 80-100% hits in BG3 a lot. As long as you find a way to gain advantage and are well equipped and statted. By level 4 most of your characters should have at least +7 to hit (2 prof + 4 stat + 1 weapon). Add in bless and advantage, you should easily hit the stronger enemies in this game (AC 17ish) easily
Base Table Top 5e is actually balanced to have your characters have
roughly a 60-65% hit-chance. Obviously, once you graduate to level 5 and get multiple attacks you'll be landing at least 1 hit much more often.
Some calculations from the Table Top community (not mine):
