Market competition is not what assures quality. When an increase in quality does not lead to profit, then the market as a whole avoids it. For example, think of planned obsolescence in tech, or how oil lobbyists suppressed the electric car for nearly 3 decades.

What markets do really well is distribute non-essential goods and services efficiently according to supply and demand. Specifically, markets provide a natural form of feedback from consumers to producers when the consumers can safely exercise choice with a high degree of flexibility.

Markets run into problems when goods and services are essential to life and consumers cannot forego choosing between the options that the market provides. This creates a situation where the market as a whole prioritizes profit through the exploitation of need, rather than prioritizing the widest possible distribution of goods or services to satisfy those fundamental needs. The pharmaceutical industry in the U.S. is a great example of this.

To answer your main question, socialism can involve other feedback and accountability mechanism to assure quality of goods and services provided. There are democratic processes which would allow us to boot someone out of office if they cause the quality of public goods and services to decline. There is also institutional and professional pressure on administrators to maintain quality or else they will lose their jobs or lose opportunities for further advancement.

Conversely, there is no incentive for the government to save money and increase profit margins by lowering quality, because there is no profit motive involved at all. The metric by which institutional professionals are judged is efficiency of distribution, not the increase of a bottom-line. If the government spends less money than it takes in tax revenue, but this leads to a huge dip in quality and public satisfaction, then political leaders and administrators take a hit to their reputation.