This may be fine for an initial hiring practice, but as you note it will become problematic in the future. Interestingly, you dodge the real source of the prob

This may be fine for an initial hiring practice, but as you note it will become problematic in the future. Interestingly, you dodge the real source of the problem (and its possible resolution) by hand-waving the "career ladder." Once you have an employee and a history of experiencing their work within the company you have the basis for deciding where pay diverges and what career ladder they wish to follow. The fundamental question you should always ask yourself regarding compensation for an existing employee is "what would it cost me to replace the value they deliver to the company?" That isn't based on title or prior work experience, it should be based on a real understanding of their work, initiative, and the other aspects of their involvement with the company that delivers value (along with a balance of possible deficiencies that reduce that value). Does that tend to produce valuations for existing personnel that may be higher than possible new hires? Sure, but then bringing on a new hire has its own costs regarding training, accumulation of institutional knowledge, etc but those are real costs that must enter the compensation equation. If an employee wishes to gain more compensation, their career ladder is to find ways to deliver more value. That isn't dependent on titles or checklists of certifications, it's based on what directly contributes to the success of the company.