PADI provide some recommendations based on certification level.
Recommended maximum depth for newly certified Open Water divers is 18m/60ft.
Recommended maximum depth for divers with further training and experience is 30m/100ft.
Recommended maximum depth for divers with specific deep dive training is 40m/130ft.
However, PADI also categorically state that divers should dive within the limits of their training and experience. They should also dive conservatively and set personal limits. Those limits are based on a wide spectrum of factors, including; water/weather conditions, personal comfort zone and capability, dive objectives and your buddies comfort zone and capability etc
That advice really over-rules any concept that you are attaining a 'license that permits you to dive to X, Y or Z depths'. Divers should make a realistic assessment of each individual dive plan and ensure that they have the training, equipment, experience and psychological comfort to complete the dive.
Such an assessment should be based on the divers own capabilities and not be swayed by any assumption that external support will make the dive safer for them. Dives conducted on the basis that you can dangerously exceed your own comfort zone, training or experience on the basis of another divers' capabilities are often called "trust me dives" - and can be a recipe for disaster.
As for training depths, these should ideally give the diver experience in the type of diving they will likely complete post-qualification. It's far from unreasonable to assume that any OW qualified diver is going to complete post-qualification dives in the full 18m/60ft depth range. Therefore, an 'ideal' course will give that diver exposure to the fullest range of depths and dive profiles (within course standards).
Having said that, the depth of a dive is merely one small factor in the training equation. Completing shallow dives on an OW course may not be ideal - but the quality of those training dives is what really matters. A good instructor is a good instructor. Bad is bad. There can be valid reasons why deeper dives were not completed - and those would normally be reasons dictated by student safety and/or the availability of depth at a training site. Dives could also be kept shallow to maximise training time for the student.
From my experience, bad instructors are normally the ones who spend dive time longest and deepest. Burn the student's air, finish the dives quick and return to shore for an early finish to work. Sad, but true - I've seen that mentality in some dive 'professionals'.