I have no dates on my cv for qualifications so they can't guess my age (important given age discrimination is so rife) but it also means they can't tell what year I entered the workforce. I then decide what point in time I want to start my cv (roughly back about 20 years maximum). At the point of shortlisting they would have no idea if I'd been working at all before that date.
I also group the early part of my career together in one generic statement "various administrative and customer service roles in X, Y, Z industries" and even fore more recent periods of time I group multiple roles and only split out the ones particularly relevant to the job I'm applying for (one grouping of various fixed term/ interim roles covers 4 years).
I've been working for over 35 years, there's no way I can list every job and the gaps between them on my c.v! It would be ridiculously long, plus I don't remember exact dates for many of them (maybe month and year at a push).
If I'm going for job that needs higher level referencing & security clearance like police or civil service or some education posts they usually only go back about 10 years and I can provide details when asked. If I am DBS checked then any unspent convictions or ones that don't get removed from the record will show up anyway. So these sorts of reasons for having a complete exact record on your cv are not accurate.
If you are applying for a role that come under safeguarding you can state in the covering letter or statement that precise dates for all jobs held and gaps in employment for travelling/not working/maternity leave/career breaks etc can be provided on request.
Also withe online applications it can take forever to add each separate role you'd ever held. Even when applicant systems extract information from your cv you nearly always have to tweak for accuracy. Once you hit a certain age or have had a lot of jobs then listing every job and gap is just impracticable.
Should add, I work in HR so see this from both sides.