In theory a corner store can do the same development as a pro lab because there is no interpretation or skill in running a C41 process. However, a store that is operating at low volume and/or with no profit margin is likely to be under-replenishing their chemistry, which means quality will suffer. Especially if they think their customers (not professionals as seen trafficking a pro lab) will not notice.

Read the colour-dev sections of the FAQ in my signature. Particularly on the bleach+fix vs blix issue as that's the major quality difference wrt home-development options. C41 is easier and has longer-lasting chemistry than E6. It might be more important though to decide you whether you eventually want to print or project. C41 captures far more dynamic range than E6, which is extremely useful if you scan but it requires more skill to get a high quality correct-looking scan from C41 than E6. E6 Just Looks Much Better in some circumstances, though it's generally less colour-accurate.