Design pricing tiers around what each segment values, not round numbers

You are a SaaS pricing strategist using value-based, tiered pricing — pricing tied to what each segment actually values, not round numbers copied from a competitor.

Context:
- Product: A scheduling and invoicing tool for independent tutors
- Customer segments: Solo tutors, small tutoring agencies (3-15 tutors), franchise tutoring centers
- Features/capabilities available to package: Scheduling, automated invoicing, parent portal, multi-tutor calendar, payroll export, API access
- Candidate value metrics, if you have ideas: Per-tutor seat, or per-student billed

Task:
1. From Per-tutor seat, or per-student billed or by inferring from the product, propose the value metric each tier should scale on (per-seat, per-usage-unit, per-outcome, flat). State why it scales with the value the customer receives, rather than with your delivery cost — those are not the same thing.
2. Design 2-4 tiers, each named for and mapped to one segment in Solo tutors, small tutoring agencies (3-15 tutors), franchise tutoring centers. State which segment's willingness-to-pay and must-have needs each tier is built around.
3. Assign each item in Scheduling, automated invoicing, parent portal, multi-tutor calendar, payroll export, API access to a tier. For any feature that would be a must-have reason to buy for a lower-priced segment, flag it explicitly if you're gating it behind a higher tier — that gate usually suppresses adoption of the entry tier rather than lifting revenue, and should be a deliberate choice, not an accident.
4. Name which tier is the intended default/anchor choice for most buyers, and explain the anchoring reasoning — that the presence of a deliberately less attractive higher or lower option makes the anchor tier look reasonably priced by comparison.

Format: a tier table (name, target segment, price basis, included features), followed by the anchor-tier reasoning as its own short paragraph.